自定义带边框TextView--边框粗细不一的问题
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自定义带边框TextView
给textview加边框
最low的做法、textview外层套一层布局,然后给布局加边框样式(这么弱的做法,不能这么干)
自定义控件
canvas.drawLines
用canvas画四个点
package com.example.csy.activitypractice;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
/**
* @author CSY
* Created by CSY on 2018/12/3.
*/
public class BorderTextView extends android.support.v7.widget.AppCompatTextView {
private int STROKE_WIDTH = 5;
public BorderTextView(Context context) {
super(context);
}
public BorderTextView(Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
}
public BorderTextView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
Paint paint = new Paint();
paint.setColor(Color.BLACK);
//边框宽度
paint.setStrokeWidth(STROKE_WIDTH);
//空心
paint.setStyle(Paint.Style.STROKE);
//抗锯齿
paint.setAntiAlias(true);
//画线
float[] points = {
0, 0, this.getWidth(), 0,
0, 0, 0, this.getHeight(),
this.getWidth(), 0, this.getWidth(), this.getHeight(),
0, this.getHeight(), this.getWidth(), this.getHeight()};
canvas.drawLines(points, paint);
}
}
canvas.drawRect
canva直接提供了画矩形的方法
drawRect(float left, float top, float right, float bottom, Paint paint) 画矩形
RectF rectF = new RectF(0, 0, this.getWidth(), this.getHeight());
canvas.drawRect(rectF, paint);
canvas.drawRoundRect
之前用Rect画了带矩形边框。现在升级一下画圆角边框
RectF rectF = new RectF(0, 0, this.getWidth(), this.getHeight());
canvas.drawRoundRect(rectF, 20, 20, paint);
如下图
canvas.drawPath
用drawRoundRect出现了粗细不一的边框,怀疑是因为用的裁剪。
所以尝试使用画路径的方法
Path path = new Path();
RectF rectF = new RectF(0, 0, this.getWidth(), this.getHeight());
path.addRoundRect(rectF, 20, 20, Path.Direction.CCW);
canvas.drawPath(path, paint);
但是效果与drawRoundRect一致
边框粗细不一致的问题需要看下自定义view
怀疑是因为边框被裁减了,所以画了两条线,一条从(0,0)开始,另一条从(100,0)开始
Paint paint = new Paint();
paint.setColor(Color.RED);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(50);
canvas.drawLine(0,0,0,500,paint);
canvas.drawLine(100,0,100,500,paint);
得到的图片如下图所示:
因此得出
画笔的起始在边框的中间,如若从(0,0)开始画,边框的一半就会被画在画布的外面。
解决
设置padding,减去边框的粗细
Path path = new Path();
RectF rectF = new RectF(STROKE_WIDTH / 2, STROKE_WIDTH / 2, this.getWidth() - (STROKE_WIDTH / 2), this.getHeight() - (STROKE_WIDTH / 2));
path.addRoundRect(rectF, 20, 20, Path.Direction.CCW);
canvas.drawPath(path, paint);
总结
通过本次自定义View的实践,应用了绘图的基础知识,顺带解决了下边框粗细不一的这个问题。这次的应用才只是自定义View的入门——绘图基础的应用而已。后面还有视图动画和属性动画等知识要掌握,加油!
来源:https://blog.csdn.net/menwaiqingshan/article/details/85157660
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