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自定义的属性如下：
具体代码如下：
import android.content.Context;import android.content.res.TypedArray;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.Path;import android.support.annotation.IntDef;import android.support.annotation.Nullable;import android.util.AttributeSet;import android.view.View;import java.lang.annotation.Retention;import java.lang.annotation.RetentionPolicy;/** * 三角形 */public class TriangleView extends View{ private Paint paint; private Path path; private int color; private int mode; private final int DEFAULT_WIDTH=48; private final int DEFAULT_HEIGHT=24; private int width = 0; private int height =0; /** * 倒三角 */ public static final int INVERTED = 0; /** * 正三角 */ public static final int REGULAR = 1; @IntDef({INVERTED, REGULAR}) @Retention(RetentionPolicy.SOURCE) public @interface ShapeMode {} public TriangleView(Context context) { this(context,null); } public TriangleView(Context context, @Nullable AttributeSet attrs) { this(context,attrs,0); } public TriangleView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); init(context,attrs); } private void init(Context context,AttributeSet attrs){ TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.TriangleView); color = typedArray.getColor(R.styleable.TriangleView_tlv_color, Color.BLACK); mode = typedArray.getInt(R.styleable.TriangleView_tlv_mode, INVERTED); typedArray.recycle(); paint = new Paint(); paint.setColor(color); paint.setAntiAlias(true); paint.setStyle(Paint.Style.FILL); path= new Path(); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); width = measureSize(widthMeasureSpec, DEFAULT_WIDTH); height = measureSize(heightMeasureSpec, DEFAULT_HEIGHT); setMeasuredDimension(width, height); } private int measureSize(int measureSpec, int defaultSize) { int newSize = 0; int mode = MeasureSpec.getMode(measureSpec); int size = MeasureSpec.getSize(measureSpec); switch (mode) { case MeasureSpec.AT_MOST: newSize = Math.min(size, defaultSize); break; case MeasureSpec.EXACTLY: newSize = size; break; case MeasureSpec.UNSPECIFIED: newSize = defaultSize; break; } return newSize; } public void setColor(int color){ this.color=color; paint.setColor(color); invalidate(); } public void setMode(@ShapeMode int mode){ this.mode=mode; invalidate(); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); drawTriangle(canvas); } private void drawTriangle(Canvas canvas) { if(mode==INVERTED) { path.moveTo(0f, 0f); path.lineTo(width, 0f); path.lineTo(width / 2.0f, height); } else { path.moveTo(width/2.0f,0f); path.lineTo(0,height); path.lineTo(width,height); } path.close(); canvas.drawPath(path, paint); }}
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