我正在尝试使用onTouch侦听器在Surfaceview上进行绘制,但是正如在GIF波纹管中看到的那样,我正在得到奇怪的图形(线条的边缘自行移动)
这是我的代码:
public class MainActivity extends AppCompatActivity implements SurfaceHolder.Callback {
SurfaceView surfaceView;
SurfaceHolder surfaceHolder;
Canvas canvas;
private Path path;
Paint mPaint = new Paint();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate( savedInstanceState );
setContentView( R.layout.activity_main );
surfaceView = (SurfaceView) findViewById( R.id.surfaceView );
surfaceHolder = surfaceView.getHolder();
surfaceView.getHolder().addCallback( this );
canvas = surfaceView.getHolder().lockCanvas();
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( 50);
}
@SuppressLint("ClickableViewAccessibility")
@Override
public void surfaceCreated(SurfaceHolder holder) {
Log.d( "surfaceCreated", "surfaceCreated " );
path = new Path();
surfaceHolder = holder;
surfaceView.setOnTouchListener( new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
float X = event.getX();
float Y = event.getY();
switch (event.getActionMasked()) {
case MotionEvent.ACTION_DOWN:
Log.d( "surfaceCreated", "action down x="+X );
// canvas = surfaceHolder.lockCanvas();
path.moveTo(X,Y);
// mv.touch_start(X,Y);
// canvas = surfaceHolder.lockCanvas();
break;
case MotionEvent.ACTION_MOVE:
Log.d( "surfaceCreated", "action move x="+X );
path.lineTo(X,Y);
break;
case MotionEvent.ACTION_UP:
Log.d( "surfaceCreated", "action up x="+X );
path.lineTo(event.getX(),event.getY());
Canvas canvas = surfaceHolder.lockCanvas();
canvas.drawPath(path, mPaint);
path.reset();
surfaceHolder.unlockCanvasAndPost(canvas);
// mCanvas.drawLine( downx, downy, upx, upy, mPaint );
break;
}
if(path != null){
Log.d( "surfaceCreated", "path is not null"+path );
Canvas canvas = surfaceHolder.lockCanvas();
canvas.drawPath(path, mPaint);
surfaceHolder.unlockCanvasAndPost(canvas);
}
return true;
}
});
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
}
}
我该如何解决该问题?以及如何使Surfaceview变为白色,如您所见,一开始它是黑色的。谢谢!
答案 0 :(得分:2)
尝试以下操作:
1)背景问题:
根据:
https://developer.android.com/reference/android/view/SurfaceView
表面按Z顺序排列,以使其在保持其表面的窗口后面 SurfaceView; SurfaceView在其窗口上打孔以允许其 要显示的表面。视图层次结构将负责 与Surface正确合成SurfaceView的任何同级 通常会显示在其顶部。这可以用来放置 叠加层,例如Surface顶部的按钮,但请注意 完整的alpha混合会影响性能 每次表面更改时都将执行合成。
,并基于 xav的答案:Set the Background Image of a SurfaceView
为了更改表面背景颜色,您可以将surfaceHolder像素格式为透明的视图(与表面视图重叠)放置在surfaceView的顶部。
2)奇怪的绘图问题:“线的边缘自行移动”
您已经得到了答案:感谢纪尧姆·亚当
3)示例:
MainActivity.class
public class MainActivity extends AppCompatActivity implements SurfaceHolder.Callback {
private SurfaceView surfaceView;
private View surfaceBackground;
private Button b_change_surface_background_color;
private Button b_clear;
private Path path;
private Paint mPaint = new Paint();
private int[] colors = new int[]{Color.WHITE, Color.GREEN, Color.MAGENTA, Color.BLUE};
private int currentSurfaceBackgroundColor = Color.WHITE;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
b_change_surface_background_color = (Button) findViewById(R.id.b_change_surface_background_color);
b_change_surface_background_color.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
int colorIndex = new Random().nextInt(colors.length);
currentSurfaceBackgroundColor = colors[colorIndex];
changeSurfaceBackgroundColor(currentSurfaceBackgroundColor);
}
});
surfaceView = (SurfaceView) findViewById(R.id.surfaceView);
surfaceView.setZOrderOnTop(true);
surfaceView.getHolder().setFormat(PixelFormat.TRANSPARENT);
surfaceView.getHolder().addCallback(this);
surfaceBackground = (View) findViewById(R.id.surfaceBackground);
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(Color.BLACK);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(50);
}
@SuppressLint("ClickableViewAccessibility")
@Override
public void surfaceCreated(SurfaceHolder holder) {
path = new Path();
surfaceView.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
float X = event.getX();
float Y = event.getY();
switch (event.getActionMasked()) {
case MotionEvent.ACTION_DOWN:
path.reset();
path.moveTo(X, Y);
break;
case MotionEvent.ACTION_MOVE:
path.lineTo(X, Y);
break;
case MotionEvent.ACTION_UP:
path.lineTo(event.getX(),event.getY());
Canvas canvas1 = surfaceView.getHolder().lockCanvas();
canvas1.drawPath(path, mPaint);
surfaceView.getHolder().unlockCanvasAndPost(canvas1);
break;
}
if(path != null){
Canvas canvas = surfaceView.getHolder().lockCanvas();
canvas.drawPath(path, mPaint);
surfaceView.getHolder().unlockCanvasAndPost(canvas);
}
return true;
}
});
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
}
private void changeSurfaceBackgroundColor(@ColorInt int color) {
if (surfaceBackground != null) {
surfaceBackground.setBackgroundColor(color);
}
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/rl"
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Change Surface Background Color"
android:textAllCaps="false"
android:layout_alignParentTop="true"
android:id="@+id/b_change_surface_background_color">
</Button>
<SurfaceView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="@id/b_change_surface_background_color"
android:id="@+id/surfaceView">
</SurfaceView>
<View
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/surfaceBackground"
android:layout_below="@id/b_change_surface_background_color"
android:background="@android:color/white">
</View>
</RelativeLayout>
4)输出
答案 1 :(得分:1)
可能是因为您在将画布与表面视图同步之前重置了路径。
Canvas canvas = surfaceHolder.lockCanvas();
canvas.drawPath(path, mPaint);
path.reset(); // move this line out
surfaceHolder.unlockCanvasAndPost(canvas);
尝试将 path.reset()移动到 path.moveTo(X,Y)之前。
path.reset(); // add just above moveTo
path.moveTo(X,Y);
答案 2 :(得分:0)
表面视图实际上位于窗口的后面。它在窗口上打一个孔供您查看。因此,您可以在窗口中的顶部放置东西,但窗口后面什么也不会出现。因此背景色将不起作用。但是您会获得具有表面视图的画布,因此可以提供自己的颜色以在画布上绘制。
private void setRefreshColor(){
Canvas canvas = surfaceHolder.lockCanvas();
canvas.drawColor(Color.WHITE);
surfaceHolder.unlockCanvasAndPost(canvas);
}
从onSurfaceCreated()调用此函数。同样,每次刷新画布时,都需要绘制REFRESH_COLOR。