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我正在開發一個android繪圖應用程序，它有一個用於繪製的自定義視圖的相關佈局。到目前爲止，除了在縮放畫布時繪圖發生在錯誤的位置上時，它們都可以工作，所以最好顯示代碼而不是試圖解釋它。是的，我嘗試過使用path.offset，但沒有成功。主要的問題是，當它在縮放時繪製，而在正確的位置繪製時，路徑太敏感，當您的手指居中時很好，但是如果您上下/左右移動路徑移動速度比手指快。Android Java，在一個縮放畫布上繪製
package com.nick.sketchr;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Rect;
import android.view.MotionEvent;
import android.view.View;
public class CustomCanvas extends View {
private Bitmap mBitmap;
private Canvas mCanvas;
private Path mPath;
private Paint mBitmapPaint;
private Paint mPaint;
private float old_scale;
private float dmx,dmy;
private double scale;
private long timevar2;
private Rect bounds;
public CustomCanvas(Context c) {
super(c);
mPath = new Path();
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(0xFF000000);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(3);
dmx = Main_App.w/2/2;
dmy = Main_App.h/2/2;
scale = 1;
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
mBitmap = Bitmap.createBitmap(Main_App.w/2, Main_App.h/2, Bitmap.Config.ARGB_8888);
mCanvas = new Canvas(mBitmap);
mBitmap.eraseColor(Color.WHITE);
}
@Override
protected void onDraw(Canvas canvas) {
float sc = (float) scale;
canvas.scale(sc, sc, Main_App.w/2, Main_App.h/2);
canvas.drawBitmap(mBitmap, dmx, dmy, mBitmapPaint);
canvas.drawPath(mPath, mPaint);
}
private float mX, mY;
private static final float TOUCH_TOLERANCE = 4;
private void touch_start(float x, float y) {
mPath.reset();
mPath.moveTo(x, y);
mX = x;
mY = y;
}
private void touch_move(float x, float y) {
float dx = Math.abs(x - mX);
float dy = Math.abs(y - mY);
if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2);
mX = x;
mY = y;
}
}
private void touch_up() {
mPath.lineTo(mX, mY);
mPath.offset(-dmx, -dmy); //this is the problem area
//also the path shows wrong when canvas is scaled... o_o
mCanvas.drawPath(mPath, mPaint);
mPath.reset();
}
@Override
public boolean onTouchEvent(MotionEvent event){
float x = event.getX()/(float)scale+bounds.left;
float y = event.getY()/(float)scale+bounds.top;
if(event.getPointerCount() == 2){
timevar2 = event.getEventTime();
float newx = event.getX(0);
float newy = event.getY(0);
float oldx = event.getX(1);
float oldy = event.getY(1);
mPath.reset();
float equa = (float) (Math.pow(newx - oldx, 2) + Math.pow(newy - oldy, 2));
float cscale = (float) Math.sqrt(equa)/100;
float scaled = (cscale - old_scale);
if(scaled < -0.1){
if(scale > 0.1){
scale -= 0.03;
}
}
if(scaled > 0.1){
scale += 0.03;
}
dmx = (float) (((newx + oldx)/2)-(Main_App.w/2/2)*scale);
dmy = (float) (((newy + oldy)/2)-(Main_App.h/2/2)*scale);
old_scale = cscale;
invalidate();
return true;
}
long dt = event.getEventTime() - timevar2;
if(dt < 100){
return true;
}
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
touch_start(x, y);
invalidate();
break;
case MotionEvent.ACTION_MOVE:
touch_move(x, y);
invalidate();
break;
case MotionEvent.ACTION_UP:
touch_up();
invalidate();
break;
}
return true;
}
public void clear(){
mBitmap.eraseColor(Color.TRANSPARENT);
invalidate();
System.gc();
}
}