将子View画在父View的(x,y)处

package com.example.tttt;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.TextView;

/**
 * @author Administrator   将子View画在父View的(x,y)处
 *
 */
public class MyView extends View {
 public MyView(Context context, AttributeSet attrs) {
  super(context, attrs);
 }

 @Override
 protected void onDraw(Canvas canvas) {
  super.onDraw(canvas);
  TextView textView = new TextView(getContext());
  textView.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT,
    LayoutParams.WRAP_CONTENT));
  textView.setText("hlldfdf");
  textView.setBackgroundColor(Color.RED);
  System.out.println("measure前"+textView.getMeasuredWidth()+"/"+textView.getMeasuredHeight()+"/"+textView.getWidth()+"/"+textView.getHeight());
  //不能少..........,不然textView.getWidth()==0,textView.getHeight()=0
  textView.measure(textView.getMeasuredWidth(),
    textView.getMeasuredHeight());
  System.out.println("measure后"+textView.getMeasuredWidth()+"/"+textView.getMeasuredHeight()+"/"+textView.getWidth()+"/"+textView.getHeight());
  textView.layout(0, 0, textView.getMeasuredWidth(),
    textView.getMeasuredHeight());
  System.out.println("layout后"+textView.getMeasuredWidth()+"/"+textView.getMeasuredHeight()+"/"+textView.getWidth()+"/"+textView.getHeight());
  //1.将子View转成bitmap=》drawBitmap
  //频繁生成bitmap容易内存溢出.............
  Bitmap bitmap = Bitmap.createBitmap(textView.getWidth(),
    textView.getHeight(), Bitmap.Config.ARGB_8888);
  Canvas canva = new Canvas(bitmap);
  textView.draw(canva);
  
  
  Paint paint = new Paint();
  canvas.drawBitmap(bitmap, 0, 100, paint);
  System.out.println("最后"+textView.getMeasuredWidth()+"/"+textView.getMeasuredHeight()+"/"+textView.getWidth()+"/"+textView.getHeight());
  //2.画布移动到指定位置...........
  //2.canvas.save()=>canva.translate(x,y)=>textView.draw(canvas)=>canvas.restore();
  canvas.save();
  canva.translate(0, 500);
  textView.draw(canvas);
  canvas.restore();
 }

}

package com.example.testviewpager;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.view.View;

public class MyView extends View {

 public MyView(Context context, AttributeSet attrs) {
  super(context, attrs);
 }

 @Override
 protected void onDraw(Canvas canvas) {
  super.onDraw(canvas);
 
  Paint paint = new Paint();
  paint.setColor(Color.RED);
  Bitmap bitmap = BitmapFactory.decodeResource(getResources(),
    R.drawable.cat);
  Rect src = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());
  RectF dst = new RectF(400, 400, 400 + bitmap.getWidth(),
    400 + bitmap.getHeight());
  //完整图片画出，坐标在(400,400)
  canvas.drawBitmap(bitmap, src, dst, paint);
  RectF dst2 = new RectF(400, 800, 400 + bitmap.getWidth() / 2,
    800 + bitmap.getHeight() / 2);
  //完整图片画出，坐标在（400，800），只是变小了，变成原图的一半大
  canvas.drawBitmap(bitmap, src, dst2, paint);
  //从原图的（0，50）这个点开始裁剪图片
  //从原图的（0，50）这个点开始裁剪图片
  //从原图的（0，50）这个点开始裁剪图片
  Rect src3 = new Rect(0, 50, bitmap.getWidth(), bitmap.getHeight());
  RectF dst3 = new RectF(800, 400, 800 + bitmap.getWidth()-0,
    400 + bitmap.getHeight()-50);
  canvas.drawBitmap(bitmap, src3, dst3, paint);
  
 }

}