Question

以下是我的Android新画家应用程序。

但是，它并不反映以前绘制的对象。（当我触摸屏幕时，它会失去形状）

要反映以前绘制的对象，我尝试使用'Bitmap.createBitmap'方法，但它不起作用。

请帮帮我。

public class CreativePainterActivity extends Activity {

//
 //private MyView vw;
Paint mPaint;

//--Variables to store the current figure info
private float _currentStartX;       //where mouse first pressed
private float _currentStartY;
private float _currentEndX;         //where dragged to or released
private float _currentEndY;


/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}

@Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();
setContentView(new MyView(this));
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(0xFFFFFF00);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(8);
}
//view class
public class MyView extends View{

private Canvas mCanvas;
private Bitmap mBitmap;
private Paint mBitmapPaint;
Bitmap bm;

//private Paint mBitmapPaint;

public MyView(Context context){
super(context);


//ADDED
DisplayMetrics metrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metrics);

mBitmap = Bitmap.createBitmap(metrics.widthPixels, metrics.heightPixels, Bitmap.Config.ARGB_8888);
mCanvas = new Canvas(mBitmap);
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
mCanvas.drawColor(0xFFFFFFFF);
bm = BitmapFactory.decodeResource(getResources(),R.drawable.ic_launcher);
}


public void onDraw(Canvas canvas){
//canvas.drawColor(Color.LTGRAY);
canvas.drawBitmap(bm, 0, 0, mBitmapPaint);
canvas.drawLine(_currentStartX, _currentStartY, _currentEndX, _currentEndY, mPaint);
}

//Methods for touch events
public boolean onTouchEvent(MotionEvent event){
if (event.getAction() == MotionEvent.ACTION_DOWN){
_currentStartX=event.getX();
_currentStartY=event.getY();
return true;
}

if(event.getAction() == MotionEvent.ACTION_MOVE){
_currentEndX=event.getX();
_currentEndY=event.getY();
invalidate();
return true;
}
return true;
}

}//end of the class MyView

}//end of the class CreativePainterActivity

Answer 1

您需要了解有关如何绘制视图的更多信息。在您再次绘制之后，您的观点将无法保留其中的任何内容。所以，你应该以某种方式保存以前的所有东西，并重新绘制旧的东西，以及新的变化。

一个更简单的解决方案是将先前的绘图保存到位图，然后在画布上再次绘制该位图，并添加新的东西。

流程

onDraw(){
    drawBitmap(bmp);
    drawOtherStuff();
    bmp = saveOnScreenBitmap();
}

因此，每次需要保存最后绘制的位图，并重新绘制它。希望现在更清楚了。

一些示例教程： http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/graphics/FingerPaint.html

http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/graphics/TouchPaint.html

http://www.tutorialforandroid.com/2009/06/drawing-with-canvas-in-android.html

Android - 在制作绘画应用程序时失去了之前的绘图

1 个答案: