自定义视图未在自定义视图组中绘制

Question

我有一个绘制矩形的自定义视图类，我有一个自定义视图组，我正在尝试添加这些自定义视图，但不知何故视图没有正确绘制(有时只绘制一个视图(。 无法找到问题！

主要活动.java

public class MainActivity extends Activity {
private CustomTaskView customTaskView;
private FrameLayout frameLayout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
customTaskView = new CustomTaskView(MainActivity.this);

frameLayout = new FrameLayout(MainActivity.this);
frameLayout.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));

Paint blackPaint = new Paint();
blackPaint.setColor(Color.BLACK);
blackPaint.setStyle(Paint.Style.STROKE);
CustomView customView1 = new CustomView(MainActivity.this, 100, 50, 100, 300, blackPaint);
customView1.setLayoutParams(new FrameLayout.LayoutParams(FrameLayout.LayoutParams.WRAP_CONTENT, FrameLayout.LayoutParams.WRAP_CONTENT));
frameLayout.addView(customView1);

Paint redPaint = new Paint();
redPaint.setColor(Color.RED);
redPaint.setStyle(Paint.Style.STROKE);
CustomView customView2 = new CustomView(MainActivity.this, 200, 50, 300, 400, redPaint);
customView2.setLayoutParams(new FrameLayout.LayoutParams(FrameLayout.LayoutParams.WRAP_CONTENT, FrameLayout.LayoutParams.WRAP_CONTENT));
frameLayout.addView(customView2);

setContentView(frameLayout);
}
}

自定义视图.java

public class CustomView extends View {
private Paint paint;
private float l, t, r, b;
public CustomView(Context context, float l, float t, float r, float b, Paint paint) {
super(context);
this.b = b;
this.l = l;
this.r = r;
this.t = t;
this.paint = paint;
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
super.onLayout(changed, l, t, r, b);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawRect(l, t, r, b, paint);
}
}

自定义任务视图.java(自定义视图组文件(

public class CustomTaskView extends ViewGroup implements LongPressGestureListener.HandleClicks {
int width, height;
private GestureDetectorCompat mGestureDetector;
private LongPressGestureListener longPressGestureListener;
private Map<Integer, List<Point>> map;

public CustomTaskView(Context context) {
super(context);
longPressGestureListener = new LongPressGestureListener(context, CustomTaskView.this);
mGestureDetector = new GestureDetectorCompat(context, longPressGestureListener);
map = new HashMap<>();
}
public CustomTaskView(Context context, AttributeSet attrs) {
super(context, attrs);
}
public CustomTaskView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
width = getMeasuredWidth();
height = getMeasuredHeight();
}
@Override
public boolean onTouchEvent(MotionEvent event) {
mGestureDetector.onTouchEvent(event);
// Handle any other event here, if not long press.
return true;
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
}
@Override
public void handleLongClick(MotionEvent event) {
Log.e("ganesh", "handling long clicks!");
}
@Override
public void handleSingleClick(MotionEvent event) {
float xCoordinate = event.getX();
float yCoordinate = event.getY();
Point tempPoint = new Point(xCoordinate, yCoordinate);
int count = 0;
for (Map.Entry<Integer, List<Point>> entry : map.entrySet()) {
if (isPointInside(entry.getValue(), tempPoint))
count++;
}
Log.e("ganesh", "handling single clicks!" + xCoordinate + " " + yCoordinate + " count: " + count);

}

public boolean isPointInside(List<Point> pointList, Point targetPoint) {
return targetPoint.getxCoordinate() >= pointList.get(0).getxCoordinate() && targetPoint.getxCoordinate() <= pointList.get(1).getxCoordinate() && targetPoint.getyCoordinate() >= pointList.get(0).getyCoordinate() && targetPoint.getyCoordinate() <= pointList.get(2).getyCoordinate();
}

}

Answer 1

每当对自定义视图进行任何更改时，都需要重新生成项目，以便绘制 XML 预览分析器。尝试Build->Rebuild Project一次。

Answer 2

如果直接扩展 ViewGroup 类，则必须在自定义视图中提供onLayout和onMeasure方法的正确实现。您可以在此处找到有关这两种方法的更多信息 Google 开发人员指南自定义视图组

下面是对当前自定义任务视图的编辑.java以使代码正常工作。

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
int count = getChildCount();
for (int i = 0; i < count; i++) {
CustomView customView = (CustomView) this.getChildAt(i);
customView.layout(l, t, r, b);
}
}

在自定义视图中，布局方法负责在布局中定位所有子项。您需要在所有子级上调用布局方法，并为它们提供计算的左、上、右、下属性。