我只是想从头开始实现 customView，即通过扩展视图类并覆盖 onDraw() 方法。只是试图建立一个简单的视图，一个现在只画一个圆圈的视图。我在对齐它时遇到了一些问题，我无法理解 android 是如何计算视图尺寸的。只有视图即 setContentView(new MyCustomView(this)) 工作正常......它占用了整个空间并绘制了圆圈。但是，如果我施加任何限制，即给予边距，或在 centerparent 中对齐它会使我的视图完全丢失并且它不会绘制任何东西。问题是视图被其父级剪裁但无法理解为什么它被剪裁。对此的任何帮助将不胜感激。这是我的代码。
这是我的自定义视图
public class MyCustomView extends View {
private Paint myPaint=null;
private boolean useCenters;
private float xCoordinate;
private float yCoordinate;
private float viewWidth;
private float viewHeight;
private int totalTime;
private static float SWEEP_INC ;
private RectF myRect;
private boolean shouldInvalidate;
private float mSweep;
public MyCustomView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initPaintComponents();
}
public MyCustomView(Context context, AttributeSet attrs) {
this(context, attrs,0);
}
public MyCustomView(Context context) {
this(context,null);
}
private void initPaintComponents() {
myPaint = new Paint();
myPaint.setStyle(Paint.Style.STROKE);
myPaint.setStrokeWidth(4);
myPaint.setColor(0x880000FF);
useCenters = false;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
calculateCoordinates();
}
private void calculateCoordinates() {
xCoordinate = getX();
yCoordinate = getY();
viewWidth = getWidth();
viewHeight = getHeight();
myRect = new RectF(xCoordinate+3, yCoordinate+3, xCoordinate+viewWidth-(viewWidth/10), yCoordinate+viewHeight-(viewHeight/10));
Log.i("SAMPLEARC","xcoordinate: "+xCoordinate+" ycoordinate: "+yCoordinate+" view width:"+viewWidth+" view height:"+viewHeight+" measured width: "+getMeasuredWidth()+"measured height:"+getMeasuredHeight());
}
public int getTotalTime() {
return totalTime;
}
public void setTotalTime(int totalTime) {
this.totalTime = totalTime;
SWEEP_INC = (float)6/totalTime;
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawArc(myRect, 0, mSweep, useCenters, myPaint);
mSweep += SWEEP_INC;
if(mSweep > 280)
{
myPaint.setColor(0x888800FF);
}
invalidate();
}
}
我的活动：
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
MyCustomView myView = (MyCustomView) findViewById(R.id.customimg);
myView.setTotalTime(10);
}
主要的.xml
RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="@android:color/white"
com.example.anim.MyCustomView android:id="@+id/customimg"
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_centerInParent="true"
如果我在 xml 中删除该 centerInParent 它会被绘制。所以在 onMeasure() 中调用 setMeasureDimentions() 也没有任何影响。但是 xcoodinate、ycoordinate、viewWidth 和 viewHeight 似乎给出了正确的值。只需要了解视图被裁剪的原因以及 android 在运行时如何计算尺寸。以及在绘制这些自定义视图时如何考虑边距参数。任何帮助将不胜感激。
提前致谢