画布坐标显示位图不准确

Question

对于那些喜欢这个问题的人，也给它一个赞成票

我正在使用一个扩展View的类。在这个类中，我使用onDraw方法进行绘图。

当我启动我的应用程序时，除了一点烦人的事情外，一切都能正常工作。。每当我按下屏幕上的任何位置时，绘图会计算出我触摸屏幕的坐标，并应该在这些精确的坐标中绘制图像，它会将它们从我最初按下的位置画出一点。

例如，如果我在x=150，y=250的位置点击屏幕，则图像将显示大量像素。

需要明确的是，当我按下屏幕时，我希望我的图像正好显示在手指下方或非常靠近我点击的地方，然而，图像通常显示在按下位置下方100个像素左右。

在使用画布绘制坐标时，是否有我不知道的地方？

这是我的代码

public class PixelParticle extends View{
private float locationX;
private float locationY;
private int sizeX;
private int sizeY;
private Paint color;
private Rect rect;
private int paintcolor;
private float myLocX;
private float myLocY;

public PixelParticle(Context context, float locationX, float locationY, int sizeX, int sizeY, int paintcolor) {
super(context);
this.locationX = locationX;
this.locationY = locationY;
this.sizeX = sizeX;
this.sizeY = sizeY;
this.paintcolor = paintcolor;
rect = new Rect();
color = new Paint();
}
@Override
protected void onDraw(Canvas canvas){
super.onDraw(canvas);
Bitmap myBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
Bitmap resizedBitmap = Bitmap.createScaledBitmap(myBitmap, 250, 250, true);
canvas.drawBitmap(resizedBitmap,locationX ,locationY , null);
}
}

以及主要活动。。

public class MainActivity extends Activity {
private int pixelColor;
private float x;
private float y;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
x = event.getX();
y = event.getY();
pixelColor = Color.RED;
PixelParticle pp = new PixelParticle(this, x, y, 50, 50, pixelColor);
setContentView(pp); 
return false;
}
}

Answer 1

屏幕的高度包括标题和通知栏。将"活动"设为全屏并删除标题将解决问题。试试这个：

PixelParticle。。。

public class PixelParticle extends View {
private float locationX;
private float locationY;
private int sizeX;
private int sizeY;
private Paint color;
private Rect rect;
private int paintcolor;
private float myLocX;
private float myLocY;
public PixelParticle(Context context, float locationX, float locationY,
int sizeX, int sizeY, int paintcolor) {
super(context);
this.locationX = locationX;
this.locationY = locationY;
this.sizeX = sizeX;
this.sizeY = sizeY;
this.paintcolor = paintcolor;
rect = new Rect();
color = new Paint();
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
Bitmap myBitmap = BitmapFactory.decodeResource(getResources(),
R.drawable.ic_launcher);
Bitmap resizedBitmap = Bitmap.createScaledBitmap(myBitmap, 250, 250,
true);
canvas.drawBitmap(resizedBitmap, locationX
- (resizedBitmap.getWidth() / 2),
locationY - (resizedBitmap.getHeight() / 2), null);
}}

主要活动。。

public class MainActivity extends Activity {
private int pixelColor;
private float x;
private float y;
PixelParticle pp ;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
x = event.getX();
y = event.getY();
pixelColor = Color.RED;
pp = new PixelParticle(this, x, y, 50, 50, pixelColor);
setContentView(pp); 
return false;
}}