michael@0: /* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
michael@0:  * This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: package org.mozilla.gecko;
michael@0: 
michael@0: import android.content.res.Resources;
michael@0: import android.graphics.Bitmap;
michael@0: import android.graphics.BitmapShader;
michael@0: import android.graphics.Canvas;
michael@0: import android.graphics.ColorFilter;
michael@0: import android.graphics.ComposeShader;
michael@0: import android.graphics.LinearGradient;
michael@0: import android.graphics.Paint;
michael@0: import android.graphics.PixelFormat;
michael@0: import android.graphics.PorterDuff;
michael@0: import android.graphics.PorterDuffColorFilter;
michael@0: import android.graphics.Rect;
michael@0: import android.graphics.Shader;
michael@0: import android.graphics.drawable.Drawable;
michael@0: 
michael@0: /**
michael@0:  * A special drawable used with lightweight themes. This draws a color 
michael@0:  * (with an optional color-filter) and a bitmap (with a linear gradient 
michael@0:  * to specify the alpha) in order.
michael@0:  */
michael@0: public class LightweightThemeDrawable extends Drawable {
michael@0:     private Paint mPaint;
michael@0:     private Paint mColorPaint;
michael@0: 
michael@0:     private Bitmap mBitmap;
michael@0:     private Resources mResources;
michael@0: 
michael@0:     private int mStartColor;
michael@0:     private int mEndColor;
michael@0: 
michael@0:     public LightweightThemeDrawable(Resources resources, Bitmap bitmap) {
michael@0:         mBitmap = bitmap;
michael@0:         mResources = resources;
michael@0: 
michael@0:         mPaint = new Paint();
michael@0:         mPaint.setAntiAlias(true);
michael@0:         mPaint.setStrokeWidth(0.0f);
michael@0:     }
michael@0: 
michael@0:     @Override
michael@0:     protected void onBoundsChange(Rect bounds) {
michael@0:         super.onBoundsChange(bounds);
michael@0:         initializeBitmapShader();
michael@0:     }
michael@0: 
michael@0:     @Override
michael@0:     public void draw(Canvas canvas) {
michael@0:         // Draw the colors, if available.
michael@0:         if (mColorPaint != null)
michael@0:             canvas.drawPaint(mColorPaint);
michael@0: 
michael@0:         // Draw the bitmap.
michael@0:         canvas.drawPaint(mPaint);
michael@0:     }
michael@0: 
michael@0:     @Override
michael@0:     public int getOpacity() {
michael@0:         return PixelFormat.TRANSLUCENT;
michael@0:     }
michael@0: 
michael@0:     @Override
michael@0:     public void setAlpha(int alpha) {
michael@0:         // A StateListDrawable will reset the alpha value with 255.
michael@0:         // We cannot use to be the bitmap alpha.
michael@0:         mPaint.setAlpha(alpha);
michael@0:     }
michael@0: 
michael@0:     @Override
michael@0:     public void setColorFilter(ColorFilter filter) {
michael@0:         mPaint.setColorFilter(filter);
michael@0:     }		
michael@0: 
michael@0:     /**
michael@0:      * Creates a paint that paint a particular color.
michael@0:      *
michael@0:      * @param color The color to be painted.
michael@0:      */
michael@0:     public void setColor(int color) {
michael@0:         mColorPaint = new Paint(mPaint);
michael@0:         mColorPaint.setColor(color);
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * Creates a paint that paint a particular color, and a filter for the color.
michael@0:      *
michael@0:      * @param color The color to be painted.
michael@0:      * @param filter The filter color to be applied using SRC_OVER mode.
michael@0:      */
michael@0:     public void setColorWithFilter(int color, int filter) {
michael@0:         mColorPaint = new Paint(mPaint);
michael@0:         mColorPaint.setColor(color);
michael@0:         mColorPaint.setColorFilter(new PorterDuffColorFilter(filter, PorterDuff.Mode.SRC_OVER));
michael@0:     }
michael@0: 
michael@0:     /**
michael@0:      * Set the alpha for the linear gradient used with the bitmap's shader.
michael@0:      *
michael@0:      * @param startAlpha The starting alpha (0..255) value to be applied to the LinearGradient.
michael@0:      * @param startAlpha The ending alpha (0..255) value to be applied to the LinearGradient.
michael@0:      */
michael@0:     public void setAlpha(int startAlpha, int endAlpha) {
michael@0:         mStartColor = startAlpha << 24;
michael@0:         mEndColor = endAlpha << 24;
michael@0:         initializeBitmapShader();
michael@0:     }
michael@0: 
michael@0:     private void initializeBitmapShader() {
michael@0: 	// A bitmap-shader to draw the bitmap.
michael@0:         // Clamp mode will repeat the last row of pixels.
michael@0:         // Hence its better to have an endAlpha of 0 for the linear-gradient.
michael@0: 	BitmapShader bitmapShader = new BitmapShader(mBitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
michael@0: 
michael@0: 	// A linear-gradient to specify the opacity of the bitmap.
michael@0: 	LinearGradient gradient = new LinearGradient(0, 0, 0, mBitmap.getHeight(), mStartColor, mEndColor, Shader.TileMode.CLAMP);
michael@0: 
michael@0: 	// Make a combined shader -- a performance win.
michael@0:         // The linear-gradient is the 'SRC' and the bitmap-shader is the 'DST'.
michael@0: 	// Drawing the DST in the SRC will provide the opacity.
michael@0: 	mPaint.setShader(new ComposeShader(bitmapShader, gradient, PorterDuff.Mode.DST_IN));
michael@0:     }
michael@0: }