如何在 View 类中打开自定义字体？ O_0

问题描述

这是我的班级：

package com.adaptto.myapplication;

import android.content.Context;
import android.content.res.AssetManager;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.Typeface;
import android.util.AttributeSet;
import android.view.View;
import java.io.IOException;

/*e the main app Activity
 *
 * The view also refers to attributes specified in the app res/values/attrs XML
 */

public class CustomDisplayView extends View {

    //circle and text colors
    private int circleCol, labelCol;
    private int circleCol2, labelCol2;
    //label text
    private String circleText;
    //paint for drawing custom view
    private Paint circlePaint;
    AssetManager assetMgr = getResources().getAssets();
    /**
     * Constructor method for custom view
     * - calls superclass method and adds custom processing
     *
     * @param context
     * @param attrs
     */
    public CustomDisplayView(Context context, AttributeSet attrs){
        super(context, attrs);

        //paint object for drawing in onDraw
        circlePaint = new Paint();

        //get the attributes specified in attrs.xml using the name we included
        TypedArray a = context.getTheme().obtainStyledAttributes(attrs,
                R.styleable.CustomDisplayView, 0, 0);

        try {
            //get the text and colors specified using the names in attrs.xml
            circleText = a.getString(R.styleable.CustomDisplayView_circleLabel);
            circleCol = a.getInteger(R.styleable.CustomDisplayView_circleColor, 0);//0 is default
            labelCol = a.getInteger(R.styleable.CustomDisplayView_labelColor, 0);
            circleCol2 = a.getInteger(R.styleable.CustomDisplayView_circleColor2, 0);//0 is default
        } finally {
            a.recycle();
        }
    }

    /**
     * Override the onDraw method to specify custom view appearance using canvas
     */
    @Override
    protected void onDraw(Canvas canvas) {


        //get half of the width and height as we are working with a circle
        int viewWidthHalf = this.getMeasuredWidth()/2;
        int viewHeightHalf = this.getMeasuredHeight()/2;


        int viewWidthHalfS = this.getMeasuredWidth()/3;
        int viewHeightHalfS = this.getMeasuredHeight()/3;


        //get the radius as half of the width or height, whichever is smaller
        //subtract ten so that it has some space around it
        int radius = 0;
        int radius2 = 0;
        if(viewWidthHalf>viewHeightHalf)
        {
            radius=viewHeightHalf-10;

        }
        else
        {
            radius=viewWidthHalf-10;
        }
        radius2=radius/2;

        //set drawing properties
        circlePaint.setStyle(Style.FILL);
        circlePaint.setAntiAlias(true);
        //set the paint color using the circle color specified
        circlePaint.setColor(circleCol);
        //draw the circle using the properties defined
        canvas.drawCircle(viewWidthHalf, viewHeightHalf, radius, circlePaint);



        //set the paint color using the circle color specified
        circlePaint.setColor(circleCol2);

        canvas.drawCircle(viewWidthHalfS, viewHeightHalfS, radius2, circlePaint);
        //set the text color using the color specified
        circlePaint.setColor(labelCol);
        //set text properties
        circlePaint.setTextAlign(Paint.Align.CENTER);
        circlePaint.setTextSize(10);




         Typeface plain = Typeface.createFromAsset(assetMgr, "fonts/O157CbnU.TTF");


        //circlePaint.setTypeface(plain);
        canvas.drawText("Sample text in bold Helvetica", viewWidthHalfS, viewHeightHalfS,circlePaint);

        circlePaint.setTextSize(40);
        //draw the text using the string attribute and chosen properties
         canvas.drawText(circleText, viewWidthHalf, viewHeightHalf, circlePaint);
    }

    //each custom attribute should have a get and set method
    //this allows updating these properties in Java
    //we call these in the main Activity class

    /**
     * Get the current circle color
     * @return color as an int
     */
    public int getCircleColor(){
        return circleCol;
    }

    /**
     * Set the circle color
     * @param newColor new color as an int
     */
    public void setCircleColor(int newColor){
        //update the instance variable
        circleCol=newColor;
        //redraw the view
        invalidate();
        requestLayout();
    }

    /**
     * Get the current text label color
     * @return color as an int
     */
    public int getLabelColor(){
        return labelCol;
    }

    /**
     * Set the label color
     * @param newColor new color as an int
     */
    public void setLabelColor(int newColor){
        //update the instance variable
        labelCol=newColor;
        //redraw the view
        invalidate();
        requestLayout();
    }

    /**
     * Get the current label text
     * @return text as a string
     */
    public String getLabelText(){
        return circleText;
    }

    /**
     * Set the label text
     * @param newLabel text as a string
     */
    public void setLabelText(String newLabel){
        //update the instance variable
        circleText=newLabel;
        //redraw the view
        invalidate();
        requestLayout();
    }
}


}

如果这个字符串没有被注释：

//Typeface plain = Typeface.createFromAsset(assetMgr, "fonts/O157CbnU.TTF");

应用程序崩溃...