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/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.graphics;
public class LinearGradient extends GradientShader {
private java.awt.Paint mJavaPaint;
/**
* Create a shader that draws a linear gradient along a line.
*
* @param x0 The x-coordinate for the start of the gradient line
* @param y0 The y-coordinate for the start of the gradient line
* @param x1 The x-coordinate for the end of the gradient line
* @param y1 The y-coordinate for the end of the gradient line
* @param colors The colors to be distributed along the gradient line
* @param positions May be null. The relative positions [0..1] of each
* corresponding color in the colors array. If this is null, the
* the colors are distributed evenly along the gradient line.
* @param tile The Shader tiling mode
*/
public LinearGradient(float x0, float y0, float x1, float y1, int colors[], float positions[],
TileMode tile) {
super(colors, positions);
mJavaPaint = new LinearGradientPaint(x0, y0, x1, y1, mColors, mPositions, tile);
}
/**
* Create a shader that draws a linear gradient along a line.
*
* @param x0 The x-coordinate for the start of the gradient line
* @param y0 The y-coordinate for the start of the gradient line
* @param x1 The x-coordinate for the end of the gradient line
* @param y1 The y-coordinate for the end of the gradient line
* @param color0 The color at the start of the gradient line.
* @param color1 The color at the end of the gradient line.
* @param tile The Shader tiling mode
*/
public LinearGradient(float x0, float y0, float x1, float y1, int color0, int color1,
TileMode tile) {
this(x0, y0, x1, y1, new int[] { color0, color1}, null /*positions*/, tile);
}
// ---------- Custom Methods
@Override
java.awt.Paint getJavaPaint() {
return mJavaPaint;
}
/**
* Linear Gradient (Java) Paint able to handle more than 2 points, as
* {@link java.awt.GradientPaint} only supports 2 points and does not support Android's tile
* modes.
*/
private static class LinearGradientPaint extends GradientPaint {
private final float mX0;
private final float mY0;
private final float mDx;
private final float mDy;
private final float mDSize2;
public LinearGradientPaint(float x0, float y0, float x1, float y1, int colors[],
float positions[], TileMode tile) {
super(colors, positions, tile);
mX0 = x0;
mY0 = y0;
mDx = x1 - x0;
mDy = y1 - y0;
mDSize2 = mDx * mDx + mDy * mDy;
}
public java.awt.PaintContext createContext(
java.awt.image.ColorModel colorModel,
java.awt.Rectangle deviceBounds,
java.awt.geom.Rectangle2D userBounds,
java.awt.geom.AffineTransform xform,
java.awt.RenderingHints hints) {
precomputeGradientColors();
return new LinearGradientPaintContext(colorModel);
}
private class LinearGradientPaintContext implements java.awt.PaintContext {
private final java.awt.image.ColorModel mColorModel;
public LinearGradientPaintContext(java.awt.image.ColorModel colorModel) {
mColorModel = colorModel;
// FIXME: so far all this is always the same rect gotten in getRaster with an indentity matrix?
}
public void dispose() {
}
public java.awt.image.ColorModel getColorModel() {
return mColorModel;
}
public java.awt.image.Raster getRaster(int x, int y, int w, int h) {
java.awt.image.BufferedImage image = new java.awt.image.BufferedImage(w, h,
java.awt.image.BufferedImage.TYPE_INT_ARGB);
int[] data = new int[w*h];
if (mDx == 0) { // vertical gradient
// compute first column and copy to all other columns
int index = 0;
for (int iy = 0 ; iy < h ; iy++) {
int color = getColor(iy + y, mY0, mDy);
for (int ix = 0 ; ix < w ; ix++) {
data[index++] = color;
}
}
} else if (mDy == 0) { // horizontal
// compute first line in a tmp array and copy to all lines
int[] line = new int[w];
for (int ix = 0 ; ix < w ; ix++) {
line[ix] = getColor(ix + x, mX0, mDx);
}
for (int iy = 0 ; iy < h ; iy++) {
System.arraycopy(line, 0, data, iy*w, line.length);
}
} else {
int index = 0;
for (int iy = 0 ; iy < h ; iy++) {
for (int ix = 0 ; ix < w ; ix++) {
data[index++] = getColor(ix + x, iy + y);
}
}
}
image.setRGB(0 /*startX*/, 0 /*startY*/, w, h, data, 0 /*offset*/, w /*scansize*/);
return image.getRaster();
}
}
/** Returns a color for the easy vertical/horizontal mode */
private int getColor(float absPos, float refPos, float refSize) {
float pos = (absPos - refPos) / refSize;
return getGradientColor(pos);
}
/**
* Returns a color for an arbitrary point.
*/
private int getColor(float x, float y) {
// find the x position on the gradient vector.
float _x = (mDx*mDy*(y-mY0) + mDy*mDy*mX0 + mDx*mDx*x) / mDSize2;
// from it get the position relative to the vector
float pos = (float) ((_x - mX0) / mDx);
return getGradientColor(pos);
}
}
}
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