Android使用SurfaceView畫圖
布局文件layout.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<SurfaceView
android:id="@+id/surfaceview"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
</RelativeLayout>
Activity 代碼如下：
package com.example.surfaceview;
import android.app.Activity;
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.os.Bundle;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceHolder.Callback;
import android.view.SurfaceView;
import android.view.View;
import android.view.View.OnTouchListener;
public class MainActivity extends Activity {
// SurfaceHolder負責維護SurfaceView上繪制的內容
private SurfaceHolder holder;
private Paint paint;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
paint = new Paint();
// 獲取SurfaceView實例
SurfaceView surface = (SurfaceView) findViewById(R.id.surfaceview);
// 初始化SurfaceHolder對象
holder = surface.getHolder();
holder.addCallback(new Callback() {
//當surface將要被銷毀時回調該方法
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
}
//當surface被創建時回調該方法
@Override
public void surfaceCreated(SurfaceHolder holder) {
// 鎖定整個SurfaceView
Canvas canvas = holder.lockCanvas();
// 獲取背景資源
Bitmap bitmap = BitmapFactory.decodeResource(
MainActivity.this.getResources(),
R.drawable.test);
// 繪制背景
canvas.drawBitmap(bitmap, 0, 0, null);
// 繪制完成，釋放畫布，提交修改
holder.unlockCanvasAndPost(canvas);
// 重新鎖兩次，避免下次lockCanvas遮擋
holder.lockCanvas(new Rect(0, 0, 0, 0));
holder.unlockCanvasAndPost(canvas);
holder.lockCanvas(new Rect(0, 0, 0, 0));
holder.unlockCanvasAndPost(canvas);
}
//當一個surface的格式或大小發生改變時回調該方法
@Override
public void surfaceChanged(SurfaceHolder holder, int format,
int width, int height) {
}
});
surface.setOnTouchListener(new OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
// 只處理按下事件
if (event.getAction() == MotionEvent.ACTION_DOWN) {
int cx = (int) event.getX();
int cy = (int) event.getY();
System.out.println(cx+"==="+cy);
// 鎖定SurfaceView的局部區域，只更新局部內容
Canvas canvas = holder.lockCanvas(new Rect(cx - 60,
cy - 60, cx + 60, cy + 60));
// 保存canvas的當前狀態
canvas.save();
// 旋轉畫布
// canvas.rotate(30, cx, cy);
paint.setColor(Color.RED);
paint.setAntiAlias(true);
canvas.drawCircle(cx, cy, 50, paint);
// 繪制紅色方塊
// canvas.drawRect(cx - 40, cy - 40, cx, cy, paint);
// 恢復canvas之前的保存狀態
// canvas.restore();
// paint.setColor(Color.GREEN);
// // 繪制綠色方塊
// canvas.drawRect(cx, cy, cx + 40, cy + 40, paint);
// 繪制完成，釋放畫布，提交修改
holder.unlockCanvasAndPost(canvas);
}
return false;
}
});
}
}
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