Android Clipping

最新推荐文章于 2025-01-03 23:02:28 发布

iteye_17103

最新推荐文章于 2025-01-03 23:02:28 发布

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文章标签：移动开发

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publicclassClippingextendsActivity{
protectedvoidonCreate(BundlesavedInstanceState){
super.onCreate(savedInstanceState);
setContentView(newSampleView(this));
}
privatestaticclassSampleViewextendsView{
privatePaintmPaint;
privatePathmPath;
publicSampleView(Contextcontext){
super(context);
setFocusable(true);
mPaint=newPaint();
mPaint.setAntiAlias(true);
mPaint.setStrokeWidth(6);
mPaint.setTextSize(16);
mPaint.setTextAlign(Paint.Align.RIGHT);
mPath=newPath();
}
privatevoiddrawScene(Canvascanvas){
canvas.clipRect(0,0,100,100);
canvas.drawColor(Color.WHITE);
mPaint.setColor(Color.RED);
canvas.drawLine(0,0,100,100,mPaint);
mPaint.setColor(Color.GREEN);
canvas.drawCircle(30,70,30,mPaint);
mPaint.setColor(Color.BLUE);
canvas.drawText("Clipping",100,30,mPaint);
}
@OverrideprotectedvoidonDraw(Canvascanvas){
canvas.drawColor(Color.GRAY);
canvas.save();
canvas.translate(10,10);
drawScene(canvas);
canvas.restore();
canvas.save();
canvas.translate(160,10);
canvas.clipRect(10,10,90,90);
canvas.clipRect(30,30,70,70,Region.Op.DIFFERENCE);
drawScene(canvas);
canvas.restore();
canvas.save();
canvas.translate(10,160);
mPath.reset();
canvas.clipPath(mPath);//makestheclipempty
mPath.addCircle(50,50,50,Path.Direction.CCW);
canvas.clipPath(mPath,Region.Op.REPLACE);
drawScene(canvas);
canvas.restore();
canvas.save();
canvas.translate(160,160);
canvas.clipRect(0,0,60,60);
canvas.clipRect(40,40,100,100,Region.Op.UNION);
drawScene(canvas);
canvas.restore();
canvas.save();
canvas.translate(10,310);
canvas.clipRect(0,0,60,60);
canvas.clipRect(40,40,100,100,Region.Op.XOR);
drawScene(canvas);
canvas.restore();
canvas.save();
canvas.translate(160,310);
canvas.clipRect(0,0,60,60);
canvas.clipRect(40,40,100,100,Region.Op.REVERSE_DIFFERENCE);
drawScene(canvas);
canvas.restore();
}
}
}

public class Clipping extends Activity { protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(new SampleView(this)); } private static class SampleView extends View { private Paint mPaint; private Path mPath; public SampleView(Context context) { super(context); setFocusable(true); mPaint = new Paint(); mPaint.setAntiAlias(true); mPaint.setStrokeWidth(6); mPaint.setTextSize(16); mPaint.setTextAlign(Paint.Align.RIGHT); mPath = new Path(); } private void drawScene(Canvas canvas) { canvas.clipRect(0, 0, 100, 100); canvas.drawColor(Color.WHITE); mPaint.setColor(Color.RED); canvas.drawLine(0, 0, 100, 100, mPaint); mPaint.setColor(Color.GREEN); canvas.drawCircle(30, 70, 30, mPaint); mPaint.setColor(Color.BLUE); canvas.drawText("Clipping", 100, 30, mPaint); } @Override protected void onDraw(Canvas canvas) { canvas.drawColor(Color.GRAY); canvas.save(); canvas.translate(10, 10); drawScene(canvas); canvas.restore(); canvas.save(); canvas.translate(160, 10); canvas.clipRect(10, 10, 90, 90); canvas.clipRect(30, 30, 70, 70, Region.Op.DIFFERENCE); drawScene(canvas); canvas.restore(); canvas.save(); canvas.translate(10, 160); mPath.reset(); canvas.clipPath(mPath); // makes the clip empty mPath.addCircle(50, 50, 50, Path.Direction.CCW); canvas.clipPath(mPath, Region.Op.REPLACE); drawScene(canvas); canvas.restore(); canvas.save(); canvas.translate(160, 160); canvas.clipRect(0, 0, 60, 60); canvas.clipRect(40, 40, 100, 100, Region.Op.UNION); drawScene(canvas); canvas.restore(); canvas.save(); canvas.translate(10, 310); canvas.clipRect(0, 0, 60, 60); canvas.clipRect(40, 40, 100, 100, Region.Op.XOR); drawScene(canvas); canvas.restore(); canvas.save(); canvas.translate(160, 310); canvas.clipRect(0, 0, 60, 60); canvas.clipRect(40, 40, 100, 100, Region.Op.REVERSE_DIFFERENCE); drawScene(canvas); canvas.restore(); } } }

//DIFFERENCE是第一次不同于第二次的部分显示出来
//REPLACE是显示第二次的
//REVERSE_DIFFERENCE 是第二次不同于第一次的部分显示

//INTERSECT交集显示
//UNION全部显示
//XOR补集就是全集的减去交集生育部分显示

canvas.translate(float dx, float dy)方法的解释：

和j2me的translate用法一样，作用就是移动原点，默认的原点（0，0）是在屏幕左上角的，你可以通过translate（x，y）把点（x，y）作为原点

Canvas提供了ClipPath, ClipRect, ClipRegion 等方法来裁剪，通过Path, Rect ,Region 的不同组合，Android几乎可以支持任意现状的裁剪区域。

android.graphics包中定义了Point, Rect, Path, Region 这几种几何形状，Path可以为有圆弧，椭圆，二次曲线，三次曲线，线段，矩形等基本几何图形或是由这些基本几何图形组合而成，Path可以为开放或是闭合曲线。Rect提供了定义矩形的简洁方法。Region则支持通过区域的“加”，“减”，“并”，“异或”等逻辑运算由多个Region组合而成。Region.Op定义了Region支持的区域间运算种类。

Clipping 介绍有Region运算来为Canvs定义剪裁区域后，同一幅图最后显示的效果。canvas.save();和canvas.restore();用于保存和恢复Canvas的状态属性。