我正在制作绘图板应用程序。我想实现一个画在图像上的“笔”。
到目前为止,我已经创建了一个自定义的imageview:
public class CustomDraw extends ImageView {
private int color = Color.BLACK;
private float width = 4f;
private List<Holder> holderList = new ArrayList<Holder>();
private class Holder {
Path path;
Paint paint;
Holder(int color, float width) {
path = new Path();
paint = new Paint();
paint.setAntiAlias(true);
paint.setStrokeWidth(width);
paint.setColor(color);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeJoin(Paint.Join.ROUND);
paint.setStrokeCap(Paint.Cap.ROUND);
}
}
public CustomDraw(Context context) {
super(context);
init();
}
public CustomDraw(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public CustomDraw(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
private void init() {
holderList.add(new Holder(color, width));
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
for (Holder holder : holderList) {
canvas.drawPath(holder.path, holder.paint);
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
float eventX = event.getX();
float eventY = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
holderList.add(new Holder(color,width));
holderList.get(holderList.size() - 1).path.moveTo(eventX, eventY);
return true;
case MotionEvent.ACTION_MOVE:
holderList.get(holderList.size() - 1).path.lineTo(eventX, eventY);
break;
case MotionEvent.ACTION_UP:
break;
default:
return false;
}
invalidate();
return true;
}
public void resetPaths() {
for (Holder holder : holderList) {
holder.path.reset();
}
invalidate();
}
public void setBrushColor(int color) {
this.color = color;
}
public void setWidth(float width) {
this.width = width;
}
}
问题是,我如何在图像上实际绘制而不是在imageview上绘图?这意味着,我不能在图像外部绘图,当我缩放视图时,内容应该相应地缩放。我发现并尝试使用extend drawable但似乎我无法在运行时绘制。
由于
答案 0 :(得分:2)
您应该使用SurfaceView
代替。与ImageView
相比,它更先进。
请参阅此图纸:http://examples.javacodegeeks.com/android/core/ui/surfaceview/android-surfaceview-example/
这是缩放: http://android-innovation.blogspot.co.nz/2013/07/how-to-implement-pinch-and-pan-zoom-on.html