package com.example.newviewapplication;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
public class CustomView extends View {
private Paint mPainter;
public CustomView(Context context) {
super(context);
init();
}
public CustomView(Context context, @Nullable AttributeSet attrs) {
this(context, attrs,0);
init();
}
public CustomView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
TypedArray t = context.obtainStyledAttributes(attrs,R.styleable.CustomView);
int mColor = t.getColor(R.styleable.CustomView_circle_color,Color.BLUE);
t.recycle();
mPainter.setColor(mColor);
init();
}
public CustomView(Context context, @Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
}
private void init(){
mPainter = new Paint();
mPainter.setColor(Color.RED);
mPainter.setStrokeWidth(5f);
mPainter.setStyle(Paint.Style.FILL);
}
@Override
protected void onDraw(@NonNull Canvas canvas) {
super.onDraw(canvas);
//padding生效
// 获取传入的padding值
final int paddingLeft = getPaddingLeft();
final int paddingRight = getPaddingRight();
final int paddingTop = getPaddingTop();
final int paddingBottom = getPaddingBottom();
// 获取绘制内容的高度和宽度（考虑了四个方向的padding值）
int width = getWidth() - paddingLeft - paddingRight ;
int height = getHeight() - paddingTop - paddingBottom ;
// 设置圆的半径 = 宽,高最小值的2分之1
int r = Math.min(width, height)/2;
// 画出圆(蓝色)
// 圆心 = 控件的中央,半径 = 宽,高最小值的2分之1
canvas.drawCircle(paddingLeft+width/2,paddingTop+height/2,r,mPainter);
}
//wrap_content生效
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
// 获取宽-测量规则的模式和大小
int widthMode = MeasureSpec.getMode(widthMeasureSpec);
int widthSize = MeasureSpec.getSize(widthMeasureSpec);
// 获取高-测量规则的模式和大小
int heightMode = MeasureSpec.getMode(heightMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec);
// 设置wrap_content的默认宽 / 高值
// 默认宽/高的设定并无固定依据,根据需要灵活设置
// 类似TextView,ImageView等针对wrap_content均在onMeasure()对设置默认宽 / 高值有特殊处理,具体读者可以自行查看
int mWidth = 400;
int mHeight = 400;
// 当布局参数设置为wrap_content时，设置默认值
if (getLayoutParams().width == ViewGroup.LayoutParams.WRAP_CONTENT && getLayoutParams().height == ViewGroup.LayoutParams.WRAP_CONTENT) {
setMeasuredDimension(mWidth, mHeight);
// 宽 / 高任意一个布局参数为= wrap_content时，都设置默认值
} else if (getLayoutParams().width == ViewGroup.LayoutParams.WRAP_CONTENT) {
setMeasuredDimension(mWidth, heightSize);
} else if (getLayoutParams().height == ViewGroup.LayoutParams.WRAP_CONTENT) {
setMeasuredDimension(widthSize, mHeight);
}
}
}
代码报错：FATAL EXCEPTION: main
Process: com.example.newviewapplication, PID: 15829
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.newviewapplication/com.example.newviewapplication.MainActivity}: android.view.InflateException: Binary XML file line #15 in com.example.newviewapplication:layout/activity_main: Binary XML file line #15 in com.example.newviewapplication:layout/activity_main: Error inflating class com.example.newviewapplication.CustomView
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