android自定义View实现图片的绘制、旋转、缩放

1、图片

把一张JPG图片改名为image.jpg，然后拷贝到项目的res-drawable中。

2、activity_main.xml

3、MainActivity.java类

包

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.content.Context;
import android.graphics.Paint;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.graphics.Canvas;
import android.widget.LinearLayout;
import android.widget.Button;

类的实现

public class MainActivity extends Activity {
	ImageView imageView = null;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		//	动态加载图片到LinearLayout中
		imageView = new ImageView(this);
		LinearLayout ll = (LinearLayout) findViewById(R.id.imageid);
		ll.addView(imageView);
		//	向左移动
		Button btnLeft = (Button) findViewById(R.id.buttonLeft);
		btnLeft.setOnClickListener(new View.OnClickListener() {
			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
				imageView.setPosLeft();
			}
		});
		//	向右移动
		Button btnRight = (Button) findViewById(R.id.buttonRight);
		btnRight.setOnClickListener(new View.OnClickListener() {
			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
				imageView.setPosRight();
			}
		});
		
		//	向左旋转
		Button btnRotationLeft = (Button)findViewById(R.id.buttonRotationLeft);
		btnRotationLeft.setOnClickListener(new View.OnClickListener() {
			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
				imageView.setRotationLeft();
			}
		});
		//	向右旋转
		Button btnRotationRight = (Button)findViewById(R.id.buttonRotationRight);
		btnRotationRight.setOnClickListener(new View.OnClickListener() {
			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
				imageView.setRotationRight();
			}
		});
		
		//	放大图片
		Button btnEnlarge = (Button)findViewById(R.id.buttonEnlarge);
		btnEnlarge.setOnClickListener(new View.OnClickListener() {
			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
				imageView.setEnlarge();
			}
		});
		//	缩小图片
		Button btnNarrow = (Button)findViewById(R.id.buttonNarrow);
		btnNarrow.setOnClickListener(new View.OnClickListener() {
			@Override
			public void onClick(View arg0) {
				// TODO Auto-generated method stub
				imageView.setNarrow();
			}
		});
	}
	
	//	自定义图片View
	class ImageView extends View {
		private Paint paint = null;	//	画笔
		private Bitmap bitmap = null;	//	图片位图
		private Bitmap bitmapDisplay = null;
		private Matrix matrix = null;
		private int nBitmapWidth = 0;	//	图片的宽度
		private int nBitmapHeight = 0;	//	图片的高度
		private int nPosX = 120;	//	图片所在的位置X
		private int nPosY = 10;	//	图片所在的位置Y
		private float fAngle = 0.0f;	//	图片旋转
		private float fScale = 1.0f;	//	图片缩放 1.0表示为原图
		
		public ImageView(Context context) {
			super(context);
			
			paint = new Paint();
			paint.setFlags(Paint.ANTI_ALIAS_FLAG);
			
			//	加载需要操作的图片
			bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.image);
			bitmapDisplay = bitmap;
			
			matrix = new Matrix();
			//	获取图片高度和宽度
			nBitmapWidth = bitmap.getWidth();
			nBitmapHeight = bitmap.getHeight();
		}
		
		//	向左移动
		public void setPosLeft() {
			nPosX -= 10; 
		}
		//	向右移动
		public void setPosRight() {
			nPosX += 10;
		}
		
		//	向左旋转
		public void setRotationLeft() {
			fAngle--;
			setAngle();
		}
		//	向右旋转
		public void setRotationRight() {
			fAngle++;
			setAngle();
		}
		
		//	图片放大
		public void setEnlarge() {
			if (fScale < 2) {
				fScale += 0.1f;
				setScale();
			}
		}
		//	图片缩小
		public void setNarrow() {
			if (fScale > 0.5) {
				fScale -= 0.1f;
				setScale();
			}
		}
		
		//	设置旋转比例
		private void setAngle() {
			matrix.reset();
			matrix.setRotate(fAngle);
			bitmapDisplay = Bitmap.createBitmap(bitmap,0,0,nBitmapWidth,nBitmapHeight,matrix,true);
		}
		
		//	设置缩放比例
		private void setScale() {
			matrix.reset();
			matrix.postScale(fScale, fScale);
			bitmapDisplay = Bitmap.createBitmap(bitmap,0,0,nBitmapWidth,nBitmapHeight,matrix,true);
		}
		
		@Override
		protected void onDraw(Canvas canvas) {
			super.onDraw(canvas);
			canvas.drawBitmap(bitmapDisplay, nPosX, nPosY, paint);
			invalidate();
		}
	}
}

4、效果图