Horizontalscrollview里添加一个布局，该布局里在添加一个自定义的View,为什么View里用Canvas画图无法显示？

Question

Horizontalscrollviewcanvas布局

Answer 1

你的 BrokenLine 的 onMeasure 有问题吧,所以测量的时候宽高计算错误,不如把你的 onMeause 发来看看

Answer 2

哦，那个，我在BrokenLine里没有重写OnMeause()方法

Answer 3

package com.example.dell.drawchartline;import android.content.Context;
import android.content.res.Resources;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.DashPathEffect;
import android.graphics.LinearGradient;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PathEffect;
import android.graphics.Shader;
import android.view.View;import java.util.List;/**
 * Created by dell on 2014/10/8.
 */
public class BrokeLine  extends View{    private float xOryDimen;
    private float interval_left_right;
    private float margin_bottom;    private Paint paint_date,paint_brokenLine,paint_dottedLine, paint_x_axis, framPaint;
    public List<String> XLabel;     //X轴上的刻度
    public List<Integer> Data;  //具体数据    public BrokeLine(Context context,List<String> XLabel,List<Integer> Data) {
        super(context);
        setWillNotDraw(false);
        this.XLabel = XLabel;
        this.Data = Data;
        init();
    }    private void init() {
        Resources res = getResources();
        xOryDimen = res.getDimension(R.dimen.x_y_interval);
        interval_left_right = xOryDimen * 5.0f;
        margin_bottom = 8*xOryDimen * 0.2f;        paint_date = new Paint();
        paint_date.setTextSize(xOryDimen * 0.8f);
        paint_brokenLine = new Paint();
        paint_brokenLine.setStrokeWidth(xOryDimen * 0.1f);
        paint_brokenLine.setColor(getResources().getColor(R.color.blueColor));
        paint_brokenLine.setAntiAlias(true);        paint_x_axis = new Paint();
        paint_x_axis.setStrokeWidth(xOryDimen * 0.1f);
        paint_x_axis.setColor(getResources().getColor(R.color.fineColor));
        paint_x_axis.setAntiAlias(true);        paint_dottedLine = new Paint();
        //paint_dottedLine.setStrokeWidth(xOryDimen * 0.1f);
        paint_dottedLine.setStyle(Paint.Style.STROKE);
        paint_dottedLine.setColor(getResources().getColor(R.color.fineColor));        framPaint = new Paint();
        framPaint.setAntiAlias(true);
        framPaint.setStrokeWidth(2.0f);
    }    @Override
    protected void onDraw(Canvas canvas) {
        System.out.println("画X轴了");
        super.onDraw(canvas);
        paintYLine(canvas);
        paintXLine(canvas);
        paintBrokenLine(canvas);
    }    private void paintBrokenLine(Canvas canvas) {
        float xTemp = 0,yTemp = 0;
        Shader shader = new LinearGradient(0,0,0,getHeight(),
                new int[] {Color.argb(50,0,255,255),Color.argb(20,0,255,255),
                Color.argb(10,0,255,255)},null,Shader.TileMode.CLAMP);
        framPaint.setShader(shader);        for(int i = 0;i < Data.size();i++) {
            float xPoint,yPoint;
            xPoint = 5.0f + interval_left_right * i;            yPoint = getHeight() - margin_bottom - (((getHeight()-margin_bottom) / 100) * Data.get(i));
            if(i == 0) {
                paint_date.setColor(getResources().getColor(R.color.orangeColor));
                canvas.drawText(String.valueOf(Data.get(i)),xPoint,yPoint,paint_date);
            }else {
                paint_date.setColor(getResources().getColor(R.color.orangeColor));
                canvas.drawText(String.valueOf(Data.get(i)),xPoint,yPoint,paint_date);                paint_date.setColor(getResources().getColor(R.color.blueColor));
                canvas.drawCircle(xPoint,yPoint,9.5f,paint_date);                canvas.drawLine(xTemp,yTemp,xPoint,yPoint,paint_brokenLine);                Path path1 = new Path();
                path1.moveTo(xTemp,yTemp);
                path1.lineTo(xPoint,yPoint);
                path1.lineTo(xPoint,getHeight());
                path1.close();
                canvas.drawPath(path1,framPaint);                Path path2 = new Path();
                path2.moveTo(xTemp,yTemp);
                path2.lineTo(xTemp,getHeight());
                path2.lineTo(xPoint,getHeight());
                path2.close();
                canvas.drawPath(path2,framPaint);//                if(i == Data.size() - 1) {
//                    path1.
//                }            }            xTemp = xPoint;
            yTemp = yPoint;
        }
    }    private void paintYLine(Canvas canvas) {
        paint_date.setColor(getResources().getColor(R.color.fineColor));
        paint_date.setStrokeWidth(xOryDimen * 0.1f);
        canvas.drawLine(5.0f,0,5.0f,getHeight() - margin_bottom,paint_date);
        for(int i = 1;i < 11;i++) {
            paint_date.setStrokeWidth(xOryDimen * 0.08f);
            //paint_date.setColor(getResources().getColor(R.color.fineColor));
            canvas.drawText(String.valueOf(10 * i),5.0f,((getHeight() - margin_bottom) / 10) * (10 - i),paint_date );
            if(i == 5) {
                Path path = new Path();
                path.moveTo(5.0f,((getHeight() - margin_bottom) / 10) * 5);
                path.lineTo(getWidth(),((getHeight() - margin_bottom) / 10) * 5);
                PathEffect effect = new DashPathEffect(new float[] {
                        xOryDimen * 0.2f,xOryDimen * 0.2f,xOryDimen * 0.2f,xOryDimen * 0.2f
                },xOryDimen * 0.1f);
                paint_dottedLine.setPathEffect(effect);
                paint_dottedLine.setColor(getResources().getColor(R.color.orangeColor));
                canvas.drawPath(path,paint_dottedLine);
            }
        }
    }    private void paintXLine(Canvas canvas) {
        System.out.println("发哈人口哈");
        canvas.drawLine(5.0f,getHeight() - margin_bottom,getWidth(),getHeight() - margin_bottom, paint_x_axis);
        for(int i = 0;i < XLabel.size();i++) {
            paint_date.setStrokeWidth(xOryDimen * 0.08f);
            canvas.drawText(XLabel.get(i),interval_left_right * i,getHeight()-15.0f,paint_date);
            if (i < XLabel.size() - 1) {
                Path path = new Path();
                path.moveTo(0.5f + interval_left_right * (i+1),xOryDimen * 1.5f);
                path.lineTo(0.5f + interval_left_right * (i+1),getHeight() - margin_bottom);
                PathEffect effect = new DashPathEffect(new float[] {
                        xOryDimen * 0.3f, xOryDimen * 0.3f,xOryDimen * 0.3f,xOryDimen * 0.3f
                },xOryDimen * 0.1f);
                paint_dottedLine.setPathEffect(effect);
                paint_dottedLine.setColor(getResources().getColor(R.color.fineColor));
                canvas.drawPath(path,paint_dottedLine);
            }
        }
    }
}

Answer 4

原因正如我上面所说的,你没有重写 onMeasure 方法,而且你的 RelativeLayout 的布局是 wrap_content 的宽度,这样, RelativeLayout 在测量子布局的时候使用 View 默认的 onMeasure 方法,获得的测量宽高为0,所以不显示,你可以给你的 BrokenLine 加上 LayoutParmas, 然后就有显示了,或者重写 onMeasure 方法,自己设定宽高BrokeLine line = new BrokeLine(this,s,i);
        RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(400, ViewGroup.LayoutParams.MATCH_PARENT);
        line.setLayoutParams(params);