Question

如何将可绘制图像放入此画布并在此图像上绘制线条？代码如下：谢谢

package com.tutorialforandroid;

import java.util.ArrayList;

import android.app.Activity;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Path;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

/**
 * 
 * @author mendoza, almond joseph
 * From tutorial 
 *  http://www.tutorialforandroid.com/2009/06/drawing-with-canvas-in-android.html
 */
public class CanvasDrawingActivity extends  Activity   {
    private ArrayList<Path> _graphics = new ArrayList<Path>();
    private Paint mPaint;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(new DrawingPanel(this));
    mPaint = new Paint();
    mPaint.setDither(true);
    mPaint.setColor(0xFFFFFF00);
    mPaint.setStyle(Paint.Style.STROKE);
    mPaint.setStrokeJoin(Paint.Join.ROUND);
    mPaint.setStrokeCap(Paint.Cap.ROUND);
    mPaint.setStrokeWidth(3);


}
class DrawingPanel extends SurfaceView implements SurfaceHolder.Callback {
    private DrawingThread _thread;
    private Path path;

    public DrawingPanel(Context context) {
        super(context);
        getHolder().addCallback(this);
        _thread = new DrawingThread(getHolder(), this);
    }


    public boolean onTouchEvent(MotionEvent event) {
        synchronized (_thread.getSurfaceHolder()) {
            if(event.getAction() == MotionEvent.ACTION_DOWN){
                path = new Path();
                path.moveTo(event.getX(), event.getY());
                path.lineTo(event.getX(), event.getY());
            }else if(event.getAction() == MotionEvent.ACTION_MOVE){
                path.lineTo(event.getX(), event.getY());
            }else if(event.getAction() == MotionEvent.ACTION_UP){
                path.lineTo(event.getX(), event.getY());
                _graphics.add(path);
            }

            return true;
        }
    }

    @Override
    public void onDraw(Canvas canvas) {
        for (Path path : _graphics) {
            //canvas.drawPoint(graphic.x, graphic.y, mPaint);
            canvas.drawPath(path, mPaint);

        }
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int width,
                               int height) {
        // TODO Auto-generated method stub

    }

    public void surfaceCreated(SurfaceHolder holder) {
        // TODO Auto-generated method stub
        _thread.setRunning(true);
        _thread.start();
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        // TODO Auto-generated method stub
        boolean retry = true;
        _thread.setRunning(false);
        while (retry) {
            try {
                _thread.join();
                retry = false;
            } catch (InterruptedException e) {
                // we will try it again and again...
            }
        }
    }
}

class DrawingThread extends Thread {
    private SurfaceHolder _surfaceHolder;
    private DrawingPanel _panel;
    private boolean _run = false;

    public DrawingThread(SurfaceHolder surfaceHolder, DrawingPanel panel) {
        _surfaceHolder = surfaceHolder;
        _panel = panel;
    }

    public void setRunning(boolean run) {
        _run = run;
    }

    public SurfaceHolder getSurfaceHolder() {
        return _surfaceHolder;
    }

    @Override
    public void run() {
        Canvas c;
        while (_run) {
            c = null;
            try {
                c = _surfaceHolder.lockCanvas(null);
                synchronized (_surfaceHolder) {
                    _panel.onDraw(c);
                }
            } finally {
                // do this in a finally so that if an exception is thrown
                // during the above, we don't leave the Surface in an
                // inconsistent state
                if (c != null) {
                    _surfaceHolder.unlockCanvasAndPost(c);
                }
            }
        }
    }
}

}

Answer 1

在onDraw(Canvas canvas)

内

Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.icon);
canvas.drawBitmap(bitmap, x, y, null);

就在图像上画一条线，我不确定，但我认为

canvas.drawRect();

应该能够做到这一点，bitmap.getWidth()和bitmap.getheight()可以帮助你解决这个问题。

如何将可绘制图像放入此画布并在此图像上绘制线条？

1 个答案: