canvas绘制bitmap1--两个bitmap交集裁剪等效果

package com.example.xfermodesdemo;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.RectF;
import android.graphics.Shader;
import android.graphics.Xfermode;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.View;

public class MainActivity extends ActionBarActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new SampleView(this));
}

private static class SampleView extends View {
private static final int W = 64;// 宽64
private static final int H = 64;// 高64
private static final int ROW_MAX = 4;// 每行4个

private Bitmap mSrcB;
private Bitmap mDstB;
private Shader mBG; // 背景 是跳棋盘 样式 checker-board pattern

private static final Xfermode[] sModes = {
new PorterDuffXfermode(PorterDuff.Mode.CLEAR),
new PorterDuffXfermode(PorterDuff.Mode.SRC),
new PorterDuffXfermode(PorterDuff.Mode.DST),
new PorterDuffXfermode(PorterDuff.Mode.SRC_OVER),
new PorterDuffXfermode(PorterDuff.Mode.DST_OVER),
new PorterDuffXfermode(PorterDuff.Mode.SRC_IN),
new PorterDuffXfermode(PorterDuff.Mode.DST_IN),
new PorterDuffXfermode(PorterDuff.Mode.SRC_OUT),
new PorterDuffXfermode(PorterDuff.Mode.DST_OUT),
new PorterDuffXfermode(PorterDuff.Mode.SRC_ATOP),
new PorterDuffXfermode(PorterDuff.Mode.DST_ATOP),
new PorterDuffXfermode(PorterDuff.Mode.XOR),
new PorterDuffXfermode(PorterDuff.Mode.DARKEN),
new PorterDuffXfermode(PorterDuff.Mode.LIGHTEN),
new PorterDuffXfermode(PorterDuff.Mode.MULTIPLY),
new PorterDuffXfermode(PorterDuff.Mode.SCREEN) };
private static final String[] sLabels = { "Clear", "Src", "Dst",
"SrcOver", "DstOver", "SrcIn", "DstIn", "SrcOut", "DstOut",
"SrcATop", "DstATop", "Xor", "Darken", "Lighten", "Multiply",
"Screen" };

public SampleView(Context context) {
super(context);

mSrcB = makeSrc(W, H);
mDstB = makeDst(W, H);

// 棋盘样式背景
Bitmap bm = Bitmap.createBitmap(new int[] { 0xFFFFFFFF, 0xFFCCCCCC,
0xFFCCCCCC, 0xFFFFFFFF }, 2, 2, Bitmap.Config.RGB_565);

mBG = new BitmapShader(bm, Shader.TileMode.REPEAT,
Shader.TileMode.REPEAT);

Matrix m = new Matrix();
m.setScale(6, 6);// 缩放
mBG.setLocalMatrix(m);

}

@SuppressLint("DrawAllocation")
@Override
protected void onDraw(Canvas canvas) {
canvas.drawColor(Color.WHITE);

Paint labelP = new Paint(Paint.ANTI_ALIAS_FLAG);
labelP.setTextAlign(Paint.Align.CENTER);

Paint paint = new Paint();
paint.setFilterBitmap(false);

canvas.translate(15, 35);
int x = 0;
int y = 0;
for (int i = 0; i < sModes.length; i++) {
// 绘制边界
paint.setStyle(Paint.Style.STROKE);// 仅描边
paint.setShader(null);
canvas.drawRect(x - 0.5f, y - 0.5f, x + W + 0.5f, y + H + 0.5f,
paint);

// 绘制棋盘样式
paint.setStyle(Paint.Style.FILL);// 完全填充
paint.setShader(mBG);
canvas.drawRect(x, y, x + W, y + H, paint);

// 绘制src/des 到屏幕中
int sc = canvas.saveLayer(x, y, x + W, y + H, null,
Canvas.MATRIX_SAVE_FLAG | Canvas.CLIP_SAVE_FLAG
| Canvas.HAS_ALPHA_LAYER_SAVE_FLAG
| Canvas.FULL_COLOR_LAYER_SAVE_FLAG
| Canvas.CLIP_TO_LAYER_SAVE_FLAG);
canvas.translate(x, y);
canvas.drawBitmap(mDstB, 0, 0, paint);
paint.setXfermode(sModes[i]);
canvas.drawBitmap(mSrcB, 0, 0, paint);
paint.setXfermode(null);
canvas.restoreToCount(sc);

// 绘制文字
canvas.drawText(sLabels[i], x + W / 2, y - labelP.getTextSize()
/ 2, labelP);

x += W + 10;

// wrap around when we've drawn enough for one row
if ((i % ROW_MAX) == ROW_MAX - 1) {
x = 0;
y += H + 30;
}
}
}
}

/** 创建一个bitmap */
static Bitmap makeDst(int w, int h) {
Bitmap bm = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
Canvas c = new Canvas(bm);
Paint p = new Paint(Paint.ANTI_ALIAS_FLAG);// 抗锯齿
p.setColor(0xFFFFCC44);
c.drawOval(new RectF(0, 0, w * 3 / 4, h * 3 / 4), p);// 绘制椭圆
return bm;
}

/** 创建一个矩形的bitmap */
static Bitmap makeSrc(int w, int h) {
Bitmap bm = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
Canvas c = new Canvas(bm);// bitmap中的画布
Paint p = new Paint(Paint.ANTI_ALIAS_FLAG);

p.setColor(0xFF66AAFF);
c.drawRect(w / 3, h / 3, w * 19 / 20, h * 19 / 20, p);// 画矩形
return bm;
}

}