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Android example source code file (RadialGradient.java)

This example Android source code file (RadialGradient.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" TM.

Java - Android tags/keywords

gradientshader, illegalargumentexception, override, radialgradient, radialgradientpaint, radialgradientpaintcontext, tilemode

The RadialGradient.java Android example source code

/*
 * 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 RadialGradient extends GradientShader {

    private RadialGradientPaint mPaint;

    /**
     * Create a shader that draws a radial gradient given the center and radius.
     *
     * @param x The x-coordinate of the center of the radius
     * @param y The y-coordinate of the center of the radius
     * @param radius Must be positive. The radius of the circle for this
     *            gradient
     * @param colors The colors to be distributed between the center and edge of
     *            the circle
     * @param positions May be NULL. The relative position of each corresponding
     *            color in the colors array. If this is NULL, the the colors are
     *            distributed evenly between the center and edge of the circle.
     * @param tile The Shader tiling mode
     */
    public RadialGradient(float x, float y, float radius, int colors[], float positions[],
            TileMode tile) {
        super(colors, positions);
        if (radius <= 0) {
            throw new IllegalArgumentException("radius must be > 0");
        }

        mPaint = new RadialGradientPaint(x, y, radius, mColors, mPositions, tile);
    }

    /**
     * Create a shader that draws a radial gradient given the center and radius.
     *
     * @param x The x-coordinate of the center of the radius
     * @param y The y-coordinate of the center of the radius
     * @param radius Must be positive. The radius of the circle for this
     *            gradient
     * @param color0 The color at the center of the circle.
     * @param color1 The color at the edge of the circle.
     * @param tile The Shader tiling mode
     */
    public RadialGradient(float x, float y, float radius, int color0, int color1, TileMode tile) {
        this(x, y, radius, new int[] { color0, color1 }, null /* positions */, tile);
    }

    @Override
    java.awt.Paint getJavaPaint() {
        return mPaint;
    }

    private static class RadialGradientPaint extends GradientPaint {

        private final float mX;
        private final float mY;
        private final float mRadius;

        public RadialGradientPaint(float x, float y, float radius, int[] colors, float[] positions, TileMode mode) {
            super(colors, positions, mode);
            mX = x;
            mY = y;
            mRadius = radius;
        }

        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 RadialGradientPaintContext(colorModel);
        }

        private class RadialGradientPaintContext implements java.awt.PaintContext {

            private final java.awt.image.ColorModel mColorModel;

            public RadialGradientPaintContext(java.awt.image.ColorModel colorModel) {
                mColorModel = colorModel;
            }

            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];

                // compute distance from each point to the center, and figure out the distance from
                // it.
                int index = 0;
                for (int iy = 0 ; iy < h ; iy++) {
                    for (int ix = 0 ; ix < w ; ix++) {
                        float _x = x + ix - mX;
                        float _y = y + iy - mY;
                        float distance = (float) Math.sqrt(_x * _x + _y * _y);

                        data[index++] = getGradientColor(distance / mRadius);
                    }
                }

                image.setRGB(0 /*startX*/, 0 /*startY*/, w, h, data, 0 /*offset*/, w /*scansize*/);

                return image.getRaster();
            }

        }
    }

}

Other Android examples (source code examples)

Here is a short list of links related to this Android RadialGradient.java source code file:

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