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javax.microedition.lcdui
Class Graphics

java.lang.Object
  |
  +--javax.microedition.lcdui.Graphics

public class Graphics
extends Object

Provides simple 2D geometric rendering capability. Drawing primitives are provided for text, images, lines, rectangles, and arcs. Rectangles and arcs may also be filled with a solid color. Rectangles may also be specified with rounded corners.

The only drawing operation provided is pixel replacement. The destination pixel value is simply replaced by the current pixel value specified in the graphics object being used for rendering. No facility for combining pixel values, such as raster-ops or alpha blending, is provided.

A 24-bit color model is provided, with 8 bits for each of red, green, and blue components of a color. Not all devices support a full 24 bits' worth of color and thus they will map colors requested by the application into colors available on the device. Facilities are provided in the Display class for obtaining device characteristics, such as whether color is available and how many distinct gray levels are available. This enables applications to adapt their behavior to a device without compromising device independence.

Graphics may be rendered directly to the display or to an off-screen image buffer. The destination of rendered graphics depends on the provenance of the graphics object. A graphics object for rendering to the display is passed to the Canvas object's paint() method. This is the only means by which a graphics object may be obtained whose destination is the display. Furthermore, applications may draw using this graphics object only for the duration of the paint() method.

A graphics object for rendering to an off-screen image buffer may be obtained by calling the getGraphics() method on the desired image. A graphics object so obtained may be held indefinitely by the application, and requests may be issued on this graphics object at any time.

The default coordinate system's origin is at the upper left-hand corner of the destination. The X-axis direction is positive towards the right, and the Y-axis direction is positive downwards. Applications may assume that horizontal and vertical distances in the coordinate system represent equal distances on the actual device display, that is, pixels are square. A facility is provided for translating the origin of the coordinate system. All coordinates are specified as integers.

The coordinate system represents locations between pixels, not the pixels themselves. Therefore, the first pixel in the upper left corner of the display lies in the square bounded by coordinates (0,0) , (1,0) , (0,1) , (1,1).

Under this definition, the semantics for fill operations are clear. Since coordinate grid lines lie between pixels, fill operations affect pixels that lie entirely within the region bounded by the coordinates of the operation. For example, the operation

    g.fillRect(0, 0, 3, 2)

paints exactly six pixels. (In this example, and in all subsequent examples, the variable g is assumed to contain a reference to a Graphics object)

Each character of a font contains a set of pixels that forms the shape of the character. When a character is painted, the pixels forming the character's shape are filled with the Graphics object's current color, and the pixels not part of the character's shape are left untouched. drawChar(char character, int x, int y, int anchor), drawChars(char[] data, int offset, int length, int x, int y, int anchor), drawString(String str, int x, int y, int anchor), and #drawSubstring(String, int, int, int, int, int) drawSubstring(String str, int offset, int len, int x, int y, int anchor), all draw text in this manner.

Lines, arcs, rectangles, and rounded rectangles may be drawn with either a {@link #SOLID SOLID} or {@link #DOTTED DOTTED} stroke style, as set by the {@link #setStrokeStyle(int) setStrokeStyle(int)} method. The stroke style does not affect fill, text and image operations.

For the {@link #SOLID SOLID} stroke style, drawing operations are performed with a one-pixel wide pen that fills the pixel immediately below and to the right of the specified coordinate. Drawn lines touch pixels at both endpoints. Thus, the operation

    g.drawLine(0, 0, 0, 0)

paints exactly one pixel, the first pixel in the upper left corner of the display.

Drawing operations under the DOTTED stroke style will touch a subset of pixels that would have been touched under the SOLID stroke style. The frequency and length of dots is implementation-dependent. The endpoints of lines and arcs are not guaranteed to be drawn, nor are the corner points of rectangles. Dots are drawn by painting with the current color; spaces between dots are left untouched.

An artifact of the coordinate system is that the area affected by a fill operation differs slightly from the area affected by a draw operation given the same coordinates. For example, consider the operations

     g.fillRect(x, y, w, h); // 1
     g.drawRect(x, y, w, h); // 2

Statement (1) fills a rectangle w pixels wide and h pixels high. Statement (2) draws a rectangle whose left and top edges are within the area filled by statement (1). However, the bottom and right edges lie one pixel outside the filled area. This is counterintuitive, but it preserves the invariant that

     g.drawLine(x, y, x+w, y);
     g.drawLine(x+w, y, x+w, y+h);
     g.drawLine(x+w, y+h, x, y+h);
     g.drawLine(x, y+h, x, y);

has an effect identical to statement (2) above.

The exact pixels painted by drawLine() and drawArc() are not specified. Pixels touched by a fill operation must either exactly overlap or directly abut pixels touched by the corresponding draw operation. A fill operation must never leave a gap between the filled area and the pixels touched by the corresponding draw operation, nor may the fill operation touch pixels outside the area bounded by the corresponding draw operation.

There is a single clipping rectangle. Operations are provided for intersecting the current clip rectangle with a given rectangle and for setting the current clip rectangle outright. The only pixels touched by graphics operations are those that lie entirely within the clip rectangle. Pixels outside the clip rectangle are not affected by any graphics operations. It is legal to specify a clipping rectangle whose width or height is zero or negative. In this case the clipping rectangle is considered to be empty, that is, no pixels are contained within it. Therefore, if any graphics operations are issued under such a clipping rectangle, no pixels will be modified.

If a graphics operation is affected by the clip rectangle, the pixels touched by that operation must be the same ones that would be touched as if the clip rectangle did not affect the operation. For example, consider a clip rectangle (cx, cy, cw, ch) and a point (x1, y1) that lies outside this rectangle and a point (x2, y2) that lies within this rectangle. In the following code fragment:

     g.setClip(0, 0, Canvas.getWidth(), Canvas.getHeight());
     g.drawLine(x1, y1, x2, y2); // 3
     g.setClip(cx, cy, cw, ch);
     g.drawLine(x1, y1, x2, y2); // 4

The pixels touched by statement (4) must be identical to the pixels within (cx, cy, cw, ch) touched by statement (3).

Anchor Points

The drawing of text is based on "anchor points". Anchor points are used to minimize the amount of computation required when placing text. For example, in order to center a piece of text, an application needs to call stringWidth() or charWidth() to get the width and then perform a combination of subtraction and division to compute the proper location. The method to draw text is defined as follows:

     public void drawString(String text, int x, int y, int anchor);

This method draws text in the current color, using the current font with its anchor point at (x,y). The definition of the anchor point must be one of the horizontal constants ({@link #LEFT LEFT}, {@link #HCENTER HCENTER}, {@link #RIGHT RIGHT}) combined with one of the vertical constants ({@link #TOP TOP}, {@link #BASELINE BASELINE}, {@link #BOTTOM BOTTOM}) using the logical OR operator.

Vertical centering of the text is not specified since it is not considered useful, it is hard to specify, and it is burdensome to implement. Thus, the VCENTER value is not allowed in the anchor point parameter of text drawing calls.

The actual position of the bounding box of the text relative to the (x,y) location is determined by the anchor point. These anchor points occur at named locations along the outer edge of the bounding box. Thus, if f is g's current font (as returned by g.getFont()), the following calls all have identical results:

     g.drawString(str, x, y, TOP|LEFT);
     g.drawString(str, x + f.stringWidth(str)/2, y, TOP|HCENTER);
     g.drawString(str, x + f.stringWidth(str), y, TOP|RIGHT);
     g.drawString(str, x, y + f.getBaselinePosition(), BASELINE|LEFT);
     g.drawString(str, x + f.stringWidth(str)/2,
         y + f.getBaselinePosition(), BASELINE|HCENTER);
     g.drawString(str, x + f.stringWidth(str),
         y + f.getBaselinePosition(), BASELINE|RIGHT);
     g.drawString(str, x,
         y + f.getHeight(), BOTTOM|LEFT);
     g.drawString(str, x + f.stringWidth(str)/2,
         y + f.getHeight(), BOTTOM|HCENTER);
     g.drawString(str, x + f.stringWidth(str),
         y + f.getHeight(), BOTTOM|RIGHT);

For text drawing, the inter-character and inter-line spacing (leading) specified by the font designer are included as part of the values returned in the {@link Font#stringWidth(String) stringWidth()} and {@link Font#getHeight() getHeight()} calls. For example, given the following code:

     // (5)
     g.drawString(string1+string2, x, y, TOP|LEFT);

     // (6)
     g.drawString(string1, x, y, TOP|LEFT);
     Font f = Font.getFont();
     g.drawString(string2, x + f.stringWidth(string1), y, TOP|LEFT);

Code fragments (5) and (6) behave identically. This occurs because f.stringWidth() includes the inter-character spacing. Similarly, reasonable vertical spacing may be achieved simply by adding the font height to the Y-position of subsequent lines. For example:

     g.drawString(string1, x, y, TOP|LEFT);
     g.drawString(string2, x, y + getFont().getHeight(), TOP|LEFT);

draws string1 and string2 on separate lines with an appropriate amount of inter-line spacing.

The {@link Font#stringWidth(String) stringWidth()} of the string and the {@link Font#getHeight() getHeight()} of the Font in which it is drawn define the size of the bounding box of a piece of text. As described above, this box includes inter-line and inter-character spacing. The implementation is required to put this space below and to right of the pixels actually belonging to the characters drawn. Applications that wish to position graphics closely with respect text (for example, to paint a rectangle around a string of text) may assume that there is space below and to the right of a string and that there is no space above and to the left of the string.

Anchor points are also used for positioning of images. Similar to text drawing, the anchor point for an image specifies the point on the bounding rectangle of the destination that is to positioned at the (x,y) location given in the graphics request. Unlike text, vertical centering of images is well-defined, and thus the {@link #VCENTER VCENTER} value may be used within the anchor point parameter of image drawing requests. Because images have no notion of a baseline, the BASELINE value may not be used within the anchor point parameter of image drawing requests.

Field Summary

static int BASELINE
          Constant for positioning the anchor point at the baseline of text.

static int BOTTOM
          Constant for positioning the anchor point of text and images below the text or image.

static int DOTTED
          Constant for DOTTED stroke style.

static int HCENTER
          Constant for centering text and images horizontally around the anchor point Value 1 is assigned to HCENTER.

static int LEFT
          Constant for positioning the anchor point of text and images to the left of the text or image.

static int RIGHT
          Constant for positioning the anchor point of text and images to the right of the text or image.

static int SOLID
          Constant for the SOLID stroke style Value 0 is assigned to SOLID

static int TOP
          Constant for positioning the anchor point of text and images above the text or image.

static int VCENTER
          Constant for centering images vertically around the anchor point.

Method Summary

void clipRect(int x, int y, int width, int height)
          Intersects the current clip with the specified rectangle.

void copyArea(int x_src, int y_src, int width, int height, int x_dest, int y_dest, int anchor)
          Copies the contents of a rectangular area (x_src, y_src, width, height) to a destination area, whose anchor point identified by anchor is located at (x_dest, y_dest).

void drawArc(int x, int y, int width, int height, int startAngle, int arcAngle)
          Draws the outline of a circular or elliptical arc covering the specified rectangle, using the current color and stroke style.

void drawChar(char character, int x, int y, int anchor)
          Draws the specified character using the current font and color.

void drawChars(char[] data, int offset, int length, int x, int y, int anchor)
          Draws the specified characters using the current font and color.

void drawImage(Image img, int x, int y, int anchor)
          Draws the specified image by using the anchor point.

void drawLine(int x1, int y1, int x2, int y2)
          Draws a line between the coordinates (x1, y1) and (x2, y2) using the current color and stroke style.

void drawRect(int x, int y, int width, int height)
          Draws the outline of the specified rectangle using the current color and stroke style.

void drawRegion(Image src, int x_src, int y_src, int width, int height, int transform, int x_dest, int y_dest, int anchor)
          Copies a region of the specified source image to a location within the destination, possibly transforming (rotating and reflecting) the image data using the chosen transform function.

void drawRGB(int[] rgbData, int offset, int scanlength, int x, int y, int width, int height, boolean processAlpha)
          Renders a series of device-independent RGB+transparency values in a specified region.

void drawRoundRect(int x, int y, int width, int height, int arcWidth, int arcHeight)
          Draws the outline of the specified rounded corner rectangle using the current color and stroke style.

void drawString(String str, int x, int y, int anchor)
          Draws the specified String using the current font and color.

void drawSubstring(String str, int offset, int len, int x, int y, int anchor)
          Draws the specified String using the current font and color.

void fillArc(int x, int y, int width, int height, int startAngle, int arcAngle)
          Fills a circular or elliptical arc covering the specified rectangle.

void fillRect(int x, int y, int width, int height)
          Fills the specified rectangle with the current color.

void fillRoundRect(int x, int y, int width, int height, int arcWidth, int arcHeight)
          Fills the specified rounded corner rectangle with the current color.

void fillTriangle(int x1, int y1, int x2, int y2, int x3, int y3)
          Fills the specified triangle will the current color.

int getBlueComponent()
          Gets the blue component of the current color.

int getClipHeight()
          Gets the height of the current clipping area.

int getClipWidth()
          Gets the width of the current clipping area.

int getClipX()
          Gets the X offset of the current clipping area, relative to the coordinate system origin of this graphics context.

int getClipY()
          Gets the Y offset of the current clipping area, relative to the coordinate system origin of this graphics context.

int getColor()
          Gets the current color.

int getDisplayColor(int color)
          Gets the color that will be displayed if the specified color is requested.

Font getFont()
          Gets the current font.

int getGrayScale()
          Gets the current grayscale value of the color being used for rendering operations.

int getGreenComponent()
          Gets the green component of the current color.

int getRedComponent()
          Gets the red component of the current color.

int getStrokeStyle()
          Gets the stroke style used for drawing operations.

int getTranslateX()
          Gets the X coordinate of the translated origin of this graphics context.

int getTranslateY()
          Gets the Y coordinate of the translated origin of this graphics context.

void setClip(int x, int y, int width, int height)
          Sets the current clip to the rectangle specified by the given coordinates.

void setColor(int RGB)
          Sets the current color to the specified RGB values.

void setColor(int red, int green, int blue)
          Sets the current color to the specified RGB values.

void setFont(Font font)
          Sets the font for all subsequent text rendering operations.

void setGrayScale(int value)
          Sets the current grayscale to be used for all subsequent rendering operations.

void setStrokeStyle(int style)
          Sets the stroke style used for drawing lines, arcs, rectangles, and rounded rectangles.

void translate(int x, int y)
          Translates the origin of the graphics context to the point (x,y) in the current coordinate system.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

BASELINE

public static final int BASELINE

Constant for positioning the anchor point at the baseline of text.

Value 64 is assigned to BASELINE.

See Also:: Constant Field Values

BOTTOM

public static final int BOTTOM

Constant for positioning the anchor point of text and images below the text or image.

Value 32 is assigned to BOTTOM.

See Also:: Constant Field Values

DOTTED

public static final int DOTTED

Constant for DOTTED stroke style.

Value 1 is assigned to DOTTED.

See Also:: Constant Field Values

HCENTER

public static final int HCENTER

Constant for centering text and images horizontally around the anchor point

Value 1 is assigned to HCENTER.

See Also:: Constant Field Values

LEFT

public static final int LEFT

Constant for positioning the anchor point of text and images to the left of the text or image.

Value 4 is assigned to LEFT.

See Also:: Constant Field Values

RIGHT

public static final int RIGHT

Constant for positioning the anchor point of text and images to the right of the text or image.

Value 8 is assigned to RIGHT.

See Also:: Constant Field Values

SOLID

public static final int SOLID

Constant for the SOLID stroke style

Value 0 is assigned to SOLID

See Also:: Constant Field Values

TOP

public static final int TOP

Constant for positioning the anchor point of text and images above the text or image.

Value 16 is assigned to TOP.

See Also:: Constant Field Values

VCENTER

public static final int VCENTER

Constant for centering images vertically around the anchor point.

Value 2 is assigned to VCENTER.

See Also:: Constant Field Values

Method Detail

clipRect

public void clipRect(int x,
                     int y,
                     int width,
                     int height)

Intersects the current clip with the specified rectangle. The resulting clipping area is the intersection of the current clipping area and the specified rectangle. This method can only be used to make the current clip smaller. To set the current clip larger, use the setClip() method. Rendering operations have no effect outside of the clipping area.

Parameters:: x - the x coordinate of the rectangle to intersect the clip with; y - the y coordinate of the rectangle to intersect the clip with; width - the width of the rectangle to intersect the clip with; height - the height of the rectangle to intersect the clip with
See Also:: setClip(int, int, int, int)

drawArc

public void drawArc(int x,
                    int y,
                    int width,
                    int height,
                    int startAngle,
                    int arcAngle)

Draws the outline of a circular or elliptical arc covering the specified rectangle, using the current color and stroke style.

The resulting arc begins at startAngle and extends for arcAngle degrees, using the current color. Angles are interpreted such that 0 degrees is at the 3 o'clock position. A positive value indicates a counter-clockwise rotation while a negative value indicates a clockwise rotation.

The center of the arc is the center of the rectangle whose origin is (x, y) and whose size is specified by the width and height arguments.

The resulting arc covers an area width + 1 pixels wide by height + 1 pixels tall. If either width or height is less than zero, nothing is drawn.

The angles are specified relative to the non-square extents of the bounding rectangle such that 45 degrees always falls on the line from the center of the ellipse to the upper right corner of the bounding rectangle. As a result, if the bounding rectangle is noticeably longer in one axis than the other, the angles to the start and end of the arc segment will be skewed farther along the longer axis of the bounds.

Parameters:: x - the x coordinate of the upper-left corner of the arc to be drawn.; y - the y coordinate of the upper-left corner of the arc to be drawn.; width - the width of the arc to be drawn; height - the height of the arc to be drawn; startAngle - the beginning angle; arcAngle - the angular extent of the arc, relative to the start angle.
See Also:: fillArc(int, int, int, int, int, int)

drawChar

public void drawChar(char character,
                     int x,
                     int y,
                     int anchor)

Draws the specified character using the current font and color.

Parameters:: character - the character to be drawn; x - the x coordinate of the anchor point; y - the y coordinate of the anchor point; anchor - the anchor point for positioning the text
Throws:: IllegalArgumentException - if anchor is not a legal value
See Also:: drawString(java.lang.String, int, int, int), drawChars(char[], int, int, int, int, int)

drawChars

public void drawChars(char[] data,
                      int offset,
                      int length,
                      int x,
                      int y,
                      int anchor)

Draws the specified characters using the current font and color.

Parameters:: data - the array of characters to be drawn; offset - the start offset in the data; length - the number of characters to be drawn; x - the x coordinate of the anchor point; y - the y coordinate of the anchor point; anchor - the anchor point for positioning the text
Throws:: ArrayIndexOutOfBoundsException - if offset and length do not specify a valid range within the data array; IllegalArgumentException - if anchor is not a legal value; NullPointerException - if data is null
See Also:: drawString(java.lang.String, int, int, int)

drawImage

public void drawImage(Image img,
                      int x,
                      int y,
                      int anchor)

Draws the specified image by using the anchor point. The image can be drawn in different positions relative to the anchor point by passing the appropriate position constants.

Parameters:: img - the specified image to be drawn; x - the x coordinate of the anchor point; y - the y coordinate of the anchor point; anchor - the anchor point for positioning the image
Throws:: IllegalArgumentException - if anchor is not a legal value; NullPointerException - if img is null
See Also:: Image

drawLine

public void drawLine(int x1,
                     int y1,
                     int x2,
                     int y2)

Draws a line between the coordinates (x1, y1) and (x2, y2) using the current color and stroke style.

Parameters:: x1 - the x coordinate of the start of the line; y1 - the y coordinate of the start of the line; x2 - the x coordinate of the end of the line; y2 - the y coordinate of the end of the line

drawRect

public void drawRect(int x,
                     int y,
                     int width,
                     int height)

Draws the outline of the specified rectangle using the current color and stroke style. The resulting rectangle will cover an area (width + 1) pixels wide by (height + 1) pixels tall. If either width or height is less than zero, nothing is drawn.

Parameters:: x - the x coordinate of the rectangle to be drawn; y - the y coordinate of the rectangle to be drawn; width - the width of the rectangle to be drawn; height - the height of the rectangle to be drawn
See Also:: fillRect(int, int, int, int)

drawRoundRect

public void drawRoundRect(int x,
                          int y,
                          int width,
                          int height,
                          int arcWidth,
                          int arcHeight)

Draws the outline of the specified rounded corner rectangle using the current color and stroke style. The resulting rectangle will cover an area (width + 1) pixels wide by (height + 1) pixels tall. If either width or height is less than zero, nothing is drawn.

Parameters:: x - the x coordinate of the rectangle to be drawn; y - the y coordinate of the rectangle to be drawn; width - the width of the rectangle to be drawn; height - the height of the rectangle to be drawn; arcWidth - the horizontal diameter of the arc at the four corners; arcHeight - the vertical diameter of the arc at the four corners
See Also:: fillRoundRect(int, int, int, int, int, int)

drawString

public void drawString(String str,
                       int x,
                       int y,
                       int anchor)

Draws the specified String using the current font and color. The (x,y) position is the position of the anchor point.

Parameters:: str - the String to be drawn; x - the x coordinate of the anchor point; y - the y coordinate of the anchor point; anchor - the anchor point for positioning the text
Throws:: NullPointerException - if str is null; IllegalArgumentException - if anchor is not a legal value
See Also:: drawChars(char[], int, int, int, int, int)

drawSubstring

public void drawSubstring(String str,
                          int offset,
                          int len,
                          int x,
                          int y,
                          int anchor)

Draws the specified String using the current font and color. The (x,y) position is the position of the anchor point.

Parameters:: str - the String to be drawn; offset - zero-based index of first character in the substring; len - length of the substring; x - the x coordinate of the anchor point; y - the y coordinate of the anchor point; anchor - the anchor point for positioning the text
Throws:: StringIndexOutOfBoundsException - if offset and length do not specify a valid range within the substring; IllegalArgumentException - if anchor is not a legal value; NullPointerException - if str is null
See Also:: drawString(String, int, int, int).

fillArc

public void fillArc(int x,
                    int y,
                    int width,
                    int height,
                    int startAngle,
                    int arcAngle)

Fills a circular or elliptical arc covering the specified rectangle.

The resulting arc begins at startAngle and extends for arcAngle degrees. Angles are interpreted such that 0 degrees is at the 3 o'clock position. A positive value indicates a counter-clockwise rotation while a negative value indicates a clockwise rotation.

The center of the arc is the center of the rectangle whose origin is (x, y) and whose size is specified by the width and height arguments.

If either width or height is zero or less, nothing is drawn.

The filled region consists of the "pie wedge" region bounded by the arc segment as if drawn by drawArc(), the radius extending from the center to this arc at startAngle degrees, and radius extending from the center to this arc at startAngle + arcAngle degrees.

Parameters:: x - the x coordinate of the upper-left corner of the arc to be filled.; y - the y coordinate of the upper-left corner of the arc to be filled.; width - the width of the arc to be filled; height - the height of the arc to be filled; startAngle - the beginning angle.; arcAngle - the angular extent of the arc, relative to the start angle.
See Also:: drawArc(int, int, int, int, int, int)

fillRect

public void fillRect(int x,
                     int y,
                     int width,
                     int height)

Fills the specified rectangle with the current color. If either width or height is zero or less, nothing is drawn.

Parameters:: x - the x coordinate of the rectangle to be filled; y - the y coordinate of the rectangle to be filled; width - the width of the rectangle to be filled; height - the height of the rectangle to be filled
See Also:: drawRect(int, int, int, int)

fillRoundRect

public void fillRoundRect(int x,
                          int y,
                          int width,
                          int height,
                          int arcWidth,
                          int arcHeight)

Fills the specified rounded corner rectangle with the current color. If either width or height is zero or less, nothing is drawn.

Parameters:: x - the x coordinate of the rectangle to be filled; y - the y coordinate of the rectangle to be filled; width - the width of the rectangle to be filled; height - the height of the rectangle to be filled; arcWidth - the horizontal diameter of the arc at the four corners; arcHeight - the vertical diameter of the arc at the four corners
See Also:: drawRoundRect(int, int, int, int, int, int)

getBlueComponent

public int getBlueComponent()

Gets the blue component of the current color.

Returns:: integer value in range 0-255
See Also:: setColor(int, int, int)

getClipHeight

public int getClipHeight()

Gets the height of the current clipping area.

Returns:: height of the current clipping area.
See Also:: clipRect(int, int, int, int), setClip(int, int, int, int)

getClipWidth

public int getClipWidth()

Gets the width of the current clipping area.

Returns:: width of the current clipping area.
See Also:: clipRect(int, int, int, int), setClip(int, int, int, int)

getClipX

public int getClipX()

Gets the X offset of the current clipping area, relative to the coordinate system origin of this graphics context. Separating the getClip operation into two methods returning integers is more performance and memory efficient than one getClip() call returning an object.

Returns:: X offset of the current clipping area
See Also:: clipRect(int, int, int, int), setClip(int, int, int, int)

getClipY

public int getClipY()

Gets the Y offset of the current clipping area, relative to the coordinate system origin of this graphics context. Separating the getClip operation into two methods returning integers is more performance and memory efficient than one getClip() call returning an object.

Returns:: Y offset of the current clipping area
See Also:: clipRect(int, int, int, int), setClip(int, int, int, int)

getColor

public int getColor()

Gets the current color.

Returns:: an integer in form 0x00RRGGBB
See Also:: setColor(int, int, int)

getFont

public Font getFont()

Gets the current font.

Returns:: current font
See Also:: Font, setFont(Font)

getGrayScale

public int getGrayScale()

Gets the current grayscale value of the color being used for rendering operations. If the color was set by setGrayScale(), that value is simply returned. If the color was set by one of the methods that allows setting of the red, green, and blue components, the value returned is computed from the RGB color components (possibly in a device-specific fashion) that best approximates the brightness of that color.

Returns:: integer value in range 0-255

getGreenComponent

public int getGreenComponent()

Gets the green component of the current color.

Returns:: integer value in range 0-255
See Also:: setColor(int, int, int)

getRedComponent

public int getRedComponent()

Gets the red component of the current color.

Returns:: integer value in range 0-255
See Also:: setColor(int, int, int)

getStrokeStyle

public int getStrokeStyle()

Gets the stroke style used for drawing operations.

Returns:: stroke style, SOLID or DOTTED

getTranslateX

public int getTranslateX()

Gets the X coordinate of the translated origin of this graphics context.

Returns:: X of current origin

getTranslateY

public int getTranslateY()

Gets the Y coordinate of the translated origin of this graphics context.

Returns:: Y of current origin

setClip

public void setClip(int x,
                    int y,
                    int width,
                    int height)

Sets the current clip to the rectangle specified by the given coordinates. Rendering operations have no effect outside of the clipping area.

Parameters:: x - the x coordinate of the new clip rectangle; y - the y coordinate of the new clip rectangle; width - the width of the new clip rectangle; height - the height of the new clip rectangle
See Also:: clipRect(int, int, int, int)

setColor

public void setColor(int RGB)

Sets the current color to the specified RGB values. All subsequent rendering operations will use this specified color. The RGB value passed in is interpreted with the least significant eight bits giving the blue component, the next eight more significant bits giving the green component, and the next eight more significant bits giving the red component. That is to say, the color component is specified in the form of 0x00RRGGBB. The high order byte of this value is ignored.

Parameters:: RGB - the color being set

setColor

public void setColor(int red,
                     int green,
                     int blue)

Sets the current color to the specified RGB values. All subsequent rendering operations will use this specified color.

Parameters:: red - The red component of the color being set in range 0-255.; green - The green component of the color being set in range 0-255.; blue - The blue component of the color being set in range 0-255.
Throws:: IllegalArgumentException - if any of the color components are outside of range 0-255.

setFont

public void setFont(Font font)

Sets the font for all subsequent text rendering operations. If font is null, it is equivalent to setFont(Font.getDefaultFont()).

Parameters:: font - the specified font
See Also:: Font, getFont(), drawString(String, int, int, int), drawChars(char[], int, int, int, int, int)

setGrayScale

public void setGrayScale(int value)

Sets the current grayscale to be used for all subsequent rendering operations. For monochrome displays, the behavior is clear. For color displays, this sets the color for all subsequent drawing operations to be a gray color equivalent to the value passed in. The value must be in the range 0-255.

Parameters:: value - the desired grayscale value
Throws:: IllegalArgumentException - if the gray value is out of range

setStrokeStyle

public void setStrokeStyle(int style)

Sets the stroke style used for drawing lines, arcs, rectangles, and rounded rectangles. This does not affect fill, text, and image operations.

Parameters:: style - can be SOLID or DOTTED
Throws:: IllegalArgumentException - if the style is illegal

translate

public void translate(int x,
                      int y)

Translates the origin of the graphics context to the point (x,y) in the current coordinate system. All coordinates used in subsequent rendering operations on this graphics context will be relative to this new origin.

The effect of calls to translate() are cumulative. For example, calling translate(1, 2) and then translate(3, 4) results in a translation of (4, 6).

The application can set an absolute origin (ax, ay) using the following technique:

     g.translate(ax - g.getTranslateX(), ay - g.getTranslateY())

Parameters:: x - the x coordinate of the new translation origin; y - the y coordinate of the new translation origin
See Also:: getTranslateX(), getTranslateY()

drawRegion

public void drawRegion(Image src,
                       int x_src,
                       int y_src,
                       int width,
                       int height,
                       int transform,
                       int x_dest,
                       int y_dest,
                       int anchor)

Copies a region of the specified source image to a location within the destination, possibly transforming (rotating and reflecting) the image data using the chosen transform function.

The destination, if it is an image, must not be the same image as the source image. If it is, an exception is thrown. This restriction is present in order to avoid ill-defined behaviors that might occur if overlapped, transformed copies were permitted.

The transform function used must be one of the following, as defined in the javax.microedition.lcdui.game.Sprite class:
Sprite.TRANS_NONE - causes the specified image region to be copied unchanged
Sprite.TRANS_ROT90 - causes the specified image region to be rotated clockwise by 90 degrees.
Sprite.TRANS_ROT180 - causes the specified image region to be rotated clockwise by 180 degrees.
Sprite.TRANS_ROT270 - causes the specified image region to be rotated clockwise by 270 degrees.
Sprite.TRANS_MIRROR - causes the specified image region to be reflected about its vertical center.
Sprite.TRANS_MIRROR_ROT90 - causes the specified image region to be reflected about its vertical center and then rotated clockwise by 90 degrees.
Sprite.TRANS_MIRROR_ROT180 - causes the specified image region to be reflected about its vertical center and then rotated clockwise by 180 degrees.
Sprite.TRANS_MIRROR_ROT270 - causes the specified image region to be reflected about its vertical center and then rotated clockwise by 270 degrees.

If the source region contains transparent pixels, the corresponding pixels in the destination region must be left untouched. If the source region contains partially transparent pixels, a compositing operation must be performed with the destination pixels, leaving all pixels of the destination region fully opaque.

The x_src, y_src, width, and height parameters specify a rectangular region of the source image. It is illegal for this region to extend beyond the bounds of the source image. There is no such restriction on the destination.

The transform is applied to the image data from the region of the source image, and the result is rendered with its anchor point positioned at location (x_dest, y_dest) in the destination.

Parameters:: src - the source image to copy from; x_src - the x coordinate of the upper left corner of the region within the source image to copy; y_src - the y coordinate of the upper left corner of the region within the source image to copy; width - the width of the region to copy; height - the height of the region to copy; transform - the desired transformation for the selected region being copied; x_dest - the x coordinate of the anchor point in the destination drawing area; y_dest - the y coordinate of the anchor point in the destination drawing area; anchor - the anchor point for positioning the region within the destination image
Throws:: IllegalArgumentException - if src is the same image as the destination of this Graphics object; NullPointerException - if src is null; IllegalArgumentException - if transform is invalid; IllegalArgumentException - if anchor is invalid; IllegalArgumentException - if the region to be copied exceeds the bounds of the source image
Since:: MIDP 2.0

fillTriangle

public void fillTriangle(int x1,
                         int y1,
                         int x2,
                         int y2,
                         int x3,
                         int y3)

Fills the specified triangle will the current color. The lines connecting each pair of points are included in the filled triangle.

Parameters:: x1 - the x coordinate of the frist vertex of the triangle; y1 - the y coordinate of the first vertex of the triangle; x2 - the x coordinate of the second vertex of the triangle; y2 - the y coordinate of the second vertex of the triangle; x3 - the x coordinate of the third vertex of the triangle; y3 - the y coordinate of the third vertex of the triangle
Since:: MIDP 2.0

drawRGB

public void drawRGB(int[] rgbData,
                    int offset,
                    int scanlength,
                    int x,
                    int y,
                    int width,
                    int height,
                    boolean processAlpha)

Renders a series of device-independent RGB+transparency values in a specified region. The values are stored in rgbData in a format with 24 bits of RGB and an eight-bit alpha value (0xAARRGGBB), with the first value stored at the specified offset. The scanlength specifies the relative offset within the array between the corresponding pixels of consecutive rows; the ARGB data is assumed to be rasterized horizontally from left to right. The ARGB values are rendered in the region specified by x, y, width and height, and the operation is subject to the current clip region and translation for this Graphics object.

Mathematically, this operation can be defined as:


     P(a, b) = rgbData[offset + (a - x) + (b - y) * scanlength]

for


     x <= a < x + width
     y <= b < y + height

This capability is provided in the Graphics class so that it can be used to render both to the screen and to offscreen Image objects. The ability to retrieve ARGB values is provided by the Image.getRGB(int[], int, int, int, int, int, int) method.

If processAlpha is true, the high-order byte of the ARGB format specifies opacity; that is, 0x00RRGGBB specifies a fully transparent pixel and 0xFFRRGGBB specifies a fully opaque pixel. Intermediate alpha values specify semitransparency. If the implementation does not support alpha blending for image rendering operations, it must replace any semitransparent pixels with fully opaque or fully transparent pixels prior to performing any rendering. (See Alpha Processing for further discussion.) If processAlpha is false, the alpha values are ignored and all pixels must be treated as completely opaque.

The mapping from ARGB values to the device-dependent pixels is platform-specific and may require significant computation.

Parameters:: rgbData - An array of ARGB values in the format 0xAARRGGBB; offset - The array index of the first ARGB value; scanlength - The relative array offset between the corresponding pixels in consecutive rows in the rgbData array; x - The horizontal location of the region to be rendered; y - The vertical location of the region to be rendered; width - The width of the region to be rendered; height - The height of the region to be rendered; processAlpha - true if rgbData has an alpha channel, false if all pixels are fully opaque
Throws:: ArrayIndexOutOfBoundsException - if the requested operation will attempt to access an element of rgbData whose index is either negative or beyond its length; NullPointerException - if rgbData is null
Since:: MIDP 2.0

copyArea

public void copyArea(int x_src,
                     int y_src,
                     int width,
                     int height,
                     int x_dest,
                     int y_dest,
                     int anchor)

Copies the contents of a rectangular area (x_src, y_src, width, height) to a destination area, whose anchor point identified by anchor is located at (x_dest, y_dest). The effect must be that the destination area contains an exact copy of the contents of the source area immediately prior to the invocation of this method. This result must occur even if the source and destination areas overlap.

It is illegal for the source region to extend beyond the bounds of the image. However, it is legal for the destination to extend beyond the bounds of the image.

The copyArea method is allowed on all Graphics objects except those whose destination is the actual display device. This restriction is necessary because allowing a copyArea method on the display would adversely impact certain techniques for implementing double-buffering.

Like other graphics operations, the copyArea method uses the Source Over Destination rule for combining pixels. However, since it is defined only for mutable images, which can contain only fully opaque pixels, this is effectively the same as pixel replacement.

Parameters:: x_src - the x coordinate of upper left corner of source area; y_src - the y coordinate of upper left corner of source area; width - the width of the source area; height - the height of the source area; x_dest - the x coordinate of the destination anchor point; y_dest - the y coordinate of the destination anchor point; anchor - the anchor point for positioning the region within the destination image
Throws:: IllegalStateException - if the destination of this Graphics object is the display device; IllegalArgumentException - if the region to be copied exceeds the bounds of the source image
Since:: MIDP 2.0

getDisplayColor

public int getDisplayColor(int color)

Gets the color that will be displayed if the specified color is requested. This method enables the developer to check the manner in which RGB values are mapped to the set of distinct colors that the device can actually display. For example, with a monochrome device, this method will return either 0xFFFFFF (white) or 0x000000 (black) depending on the brightness of the specified color.

Parameters:: color - The desired color (in 0x00RRGGBB format, the high-order byte is ignored)
Returns:: the corresponding color that will be displayed on the device's screen (in 0x00RRGGBB format)
Since:: MIDP 2.0

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Field Summary
`static int`	`BASELINE` Constant for positioning the anchor point at the baseline of text.
`static int`	`BOTTOM` Constant for positioning the anchor point of text and images below the text or image.
`static int`	`DOTTED` Constant for DOTTED stroke style.
`static int`	`HCENTER` Constant for centering text and images horizontally around the anchor point Value 1 is assigned to HCENTER.
`static int`	`LEFT` Constant for positioning the anchor point of text and images to the left of the text or image.
`static int`	`RIGHT` Constant for positioning the anchor point of text and images to the right of the text or image.
`static int`	`SOLID` Constant for the SOLID stroke style Value 0 is assigned to SOLID
`static int`	`TOP` Constant for positioning the anchor point of text and images above the text or image.
`static int`	`VCENTER` Constant for centering images vertically around the anchor point.

Method Summary
`void`	`clipRect(int x, int y, int width, int height)` Intersects the current clip with the specified rectangle.
`void`	`copyArea(int x_src, int y_src, int width, int height, int x_dest, int y_dest, int anchor)` Copies the contents of a rectangular area (x_src, y_src, width, height) to a destination area, whose anchor point identified by anchor is located at (x_dest, y_dest).
`void`	`drawArc(int x, int y, int width, int height, int startAngle, int arcAngle)` Draws the outline of a circular or elliptical arc covering the specified rectangle, using the current color and stroke style.
`void`	`drawChar(char character, int x, int y, int anchor)` Draws the specified character using the current font and color.
`void`	`drawChars(char[] data, int offset, int length, int x, int y, int anchor)` Draws the specified characters using the current font and color.
`void`	`drawImage(Image img, int x, int y, int anchor)` Draws the specified image by using the anchor point.
`void`	`drawLine(int x1, int y1, int x2, int y2)` Draws a line between the coordinates (x1, y1) and (x2, y2) using the current color and stroke style.
`void`	`drawRect(int x, int y, int width, int height)` Draws the outline of the specified rectangle using the current color and stroke style.
`void`	`drawRegion(Image src, int x_src, int y_src, int width, int height, int transform, int x_dest, int y_dest, int anchor)` Copies a region of the specified source image to a location within the destination, possibly transforming (rotating and reflecting) the image data using the chosen transform function.
`void`	`drawRGB(int[] rgbData, int offset, int scanlength, int x, int y, int width, int height, boolean processAlpha)` Renders a series of device-independent RGB+transparency values in a specified region.
`void`	`drawRoundRect(int x, int y, int width, int height, int arcWidth, int arcHeight)` Draws the outline of the specified rounded corner rectangle using the current color and stroke style.
`void`	`drawString(String str, int x, int y, int anchor)` Draws the specified String using the current font and color.
`void`	`drawSubstring(String str, int offset, int len, int x, int y, int anchor)` Draws the specified String using the current font and color.
`void`	`fillArc(int x, int y, int width, int height, int startAngle, int arcAngle)` Fills a circular or elliptical arc covering the specified rectangle.
`void`	`fillRect(int x, int y, int width, int height)` Fills the specified rectangle with the current color.
`void`	`fillRoundRect(int x, int y, int width, int height, int arcWidth, int arcHeight)` Fills the specified rounded corner rectangle with the current color.
`void`	`fillTriangle(int x1, int y1, int x2, int y2, int x3, int y3)` Fills the specified triangle will the current color.
`int`	`getBlueComponent()` Gets the blue component of the current color.
`int`	`getClipHeight()` Gets the height of the current clipping area.
`int`	`getClipWidth()` Gets the width of the current clipping area.
`int`	`getClipX()` Gets the X offset of the current clipping area, relative to the coordinate system origin of this graphics context.
`int`	`getClipY()` Gets the Y offset of the current clipping area, relative to the coordinate system origin of this graphics context.
`int`	`getColor()` Gets the current color.
`int`	`getDisplayColor(int color)` Gets the color that will be displayed if the specified color is requested.
`Font`	`getFont()` Gets the current font.
`int`	`getGrayScale()` Gets the current grayscale value of the color being used for rendering operations.
`int`	`getGreenComponent()` Gets the green component of the current color.
`int`	`getRedComponent()` Gets the red component of the current color.
`int`	`getStrokeStyle()` Gets the stroke style used for drawing operations.
`int`	`getTranslateX()` Gets the X coordinate of the translated origin of this graphics context.
`int`	`getTranslateY()` Gets the Y coordinate of the translated origin of this graphics context.
`void`	`setClip(int x, int y, int width, int height)` Sets the current clip to the rectangle specified by the given coordinates.
`void`	`setColor(int RGB)` Sets the current color to the specified RGB values.
`void`	`setColor(int red, int green, int blue)` Sets the current color to the specified RGB values.
`void`	`setFont(Font font)` Sets the font for all subsequent text rendering operations.
`void`	`setGrayScale(int value)` Sets the current grayscale to be used for all subsequent rendering operations.
`void`	`setStrokeStyle(int style)` Sets the stroke style used for drawing lines, arcs, rectangles, and rounded rectangles.
`void`	`translate(int x, int y)` Translates the origin of the graphics context to the point (x,y) in the current coordinate system.

javax.microedition.lcdui Class Graphics

BASELINE

BOTTOM

DOTTED

HCENTER

LEFT

RIGHT

SOLID

TOP

VCENTER

clipRect

drawArc

drawChar

drawChars

drawImage

drawLine

drawRect

drawRoundRect

drawString

drawSubstring

fillArc

fillRect

fillRoundRect

getBlueComponent

getClipHeight

getClipWidth

getClipX

getClipY

getColor

getFont

getGrayScale

getGreenComponent

getRedComponent

getStrokeStyle

getTranslateX

getTranslateY

setClip

setColor

setColor

setFont

setGrayScale

setStrokeStyle

translate

drawRegion

fillTriangle

drawRGB

copyArea

getDisplayColor

javax.microedition.lcdui
Class Graphics