Android绘制一条平坦的道路
Android绘制一条平坦的道路
提问于 2018-06-04 02:49:12
我有需要改进的代码。
这里是错误的地方:它有点慢和起伏，这意味着线条不流畅，绘图有点延迟。
public void touchStarted(Point point) {
if (null == drawingModePath) {
drawingModePath = new Path();
}
drawingModePath.moveTo(point.x, point.y);
}
public void touchMoved(Point point) {
drawingModePath.lineTo(point.x, point.y);
Bitmap bitmap = Bitmap.createBitmap((int) getWindowManager()
.getDefaultDisplay().getWidth(), (int) getWindowManager()
.getDefaultDisplay().getHeight(), Bitmap.Config.ARGB_8888);
canvas = new Canvas(bitmap);
mainDrawingView.setImageBitmap(bitmap);
// Path
paint = new Paint();
paint.setStyle(Paint.Style.STROKE);
paint.setColor(Color.WHITE);
canvas.drawPath(drawingModePath, paint);
}
public void touchEnded(Point point) {
touchMoved(point);
}本质上，这段代码所做的就是根据touchStarted、touchMoved和touchEnded绘制路径。如果有人能帮我优化一下，我将不胜感激。如果我不在每次发生touchMoved时重新创建位图，那会怎么样呢？在这里不确定...不确定..。我使用UIBezierPath在iOS上执行这段代码，速度更快(也更流畅)。不管怎样，我来找你帮忙。感谢您的投入。
回答 1
Stack Overflow用户
回答已采纳
发布于 2018-06-04 11:20:15
你的一举一动都在重现一切。这将很大程度上影响绘图的性能。事件每8毫秒触发一次(或16毫秒我不确定)，想象一下你每8毫秒重新实例化所有东西？这很难。
，所以它必须在实例化部分中
Bitmap bitmap = Bitmap.createBitmap((int) getWindowManager()
.getDefaultDisplay().getWidth(), (int) getWindowManager()
.getDefaultDisplay().getHeight(), Bitmap.Config.ARGB_8888);
canvas = new Canvas(bitmap);
mainDrawingView.setImageBitmap(bitmap);
paint = new Paint();
paint.setStyle(Paint.Style.STROKE);
paint.setColor(Color.WHITE);无效视图应仅记录新路径并调用touchMoved() ()以使视图重绘自身，从而调用(**onDraw()**). 方法
public void touchMoved(Point point) {
drawingModePath.lineTo(point.x, point.y);
invalidate();
}，然后实现 onDraw() 方法来进行绘图
下面是我如何在我的一个项目中做绘图界面：
public class SignatureView extends View {
public SignatureView(Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
// instantiating my paint object
paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setColor(Color.BLACK);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(5);
path = new Path();
}
@Override
protected void onSizeChanged(int xNew, int yNew, int xOld, int yOld)
{
// this is where i initialize my canvas, because in constructor, the view is not completely instantiated yet, so getting the height and width there will result in null exception.
bitmap = Bitmap.createBitmap(xNew, yNew, Bitmap.Config.ARGB_8888);
background_canvas = new Canvas(bitmap);
}
@Override
protected void onDraw(Canvas canvas)
{
// draw the new path to a buffer canvas
background_canvas.drawPath(path, paint);
// put the buffer in the real canvas
canvas.drawBitmap(bitmap, 0, 0, paint);
}
@Override
public boolean onTouchEvent(MotionEvent ev)
{
//this is like your move event, it just records the new path every move.
int action = ev.getActionMasked();
if ( action == MotionEvent.ACTION_DOWN )
{
path.moveTo(ev.getX(), ev.getY());
}
else if ( action == MotionEvent.ACTION_MOVE )
{
path.lineTo(ev.getX(), ev.getY());
// call invalidate() to make the view redraw itself, resulting in calling the onDraw() method.
invalidate();
}
else if ( action == MotionEvent.ACTION_UP )
{
onDone.method();
}
return true;
}
public void clear()
{
background_canvas.drawColor(Color.WHITE);
path.reset();
invalidate();
}
interface OnDone{
void method();
}
public void setOnDone(OnDone new_onDone)
{
onDone = new_onDone;
}
OnDone onDone;
private Paint paint;
private Bitmap bitmap;
private Canvas background_canvas;
private Path path;
public Bitmap getBitmap()
{
return bitmap;
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/50669838
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