如何将文本放入drawable中？

I'm trying to create a drawable on the fly to use as a background for a custom linearlayout. It needs to have hash marks and such (no big deal), but also have numbers labeling what the hash marks are (like a ruler). I know I can just create text elements and put them inside the linearlayout and just have the hash marks in the drawable, but I'm hoping to have them inside the drawable as well, so I don't have to do measurement calculations twice.

我正在尝试动态创建一个drawable用作自定义linearlayout的背景。它需要有哈希标记等(没什么大不了的),但也有标记哈希标记的数字(如标尺)。我知道我可以创建文本元素并将它们放在linearlayout中,并且在drawable中只有哈希标记,但我希望它们也可以在drawable中使用,所以我不必进行两次测量计算。

4 个解决方案

#1

I've read the book "Professional Android 2 Application Development" (by Reto Meier). Amongst others, it contains an example project where you create a simple compass application where you "draw" text, markers etc.

我读过“专业Android 2应用程序开发”一书(由Reto Meier撰写)。其中,它包含一个示例项目,您可以在其中创建一个简单的指南针应用程序,您可以在其中“绘制”文本,标记等

The brief explanation is that you create a class that extends the android.view.View class and overrides the onDraw(Canvas) method.

简要说明是您创建了一个扩展android.view.View类的类,并重写了onDraw(Canvas)方法。

All the source code form the book is available for download here: http://www.wrox.com/WileyCDA/WroxTitle/Professional-Android-2-Application-Development.productCd-0470565527,descCd-DOWNLOAD.html. If you download the code and look inside the project named "Chapter 4 Compass", I believe you would find what you're looking for :)

本书的所有源代码均可在此处下载:http://www.wrox.com/WileyCDA/WroxTitle/Professional-Android-2-Application-Development.productCd-0470565527,descCd-DOWNLOAD.html。如果您下载代码并查看名为“第4章指南针”的项目,我相信您会找到您要找的内容:)

#2

Here is a brief example of a TextDrawable which works like a normal drawable but lets you specify text as the only constructor variable:

下面是一个TextDrawable的简短示例,其工作方式类似于普通的drawable,但允许您将text指定为唯一的构造函数变量:

public class TextDrawable extends Drawable {

    private final String text;
    private final Paint paint;

    public TextDrawable(String text) {

        this.text = text;

        this.paint = new Paint();
        paint.setColor(Color.WHITE);
        paint.setTextSize(22f);
        paint.setAntiAlias(true);
        paint.setFakeBoldText(true);
        paint.setShadowLayer(6f, 0, 0, Color.BLACK);
        paint.setStyle(Paint.Style.FILL);
        paint.setTextAlign(Paint.Align.LEFT);
    }

    @Override
    public void draw(Canvas canvas) {
        canvas.drawText(text, 0, 0, paint);
    }

    @Override
    public void setAlpha(int alpha) {
        paint.setAlpha(alpha);
    }

    @Override
    public void setColorFilter(ColorFilter cf) {
        paint.setColorFilter(cf);
    }

    @Override
    public int getOpacity() {
        return PixelFormat.TRANSLUCENT;
    }
}

#3

Looking at Plowman's answer and trying to adjust it to my needs I stumpled upon a Class that is used for Camera in this link

看看Plowman的答案,并尝试根据我的需要调整它,我在这个链接中找到了一个用于Camera的类

Here is the code from the TextDrawable Class. Looks pretty simillar with Plowmans but for me works better:

这是TextDrawable类的代码。用Plowmans看起来很漂亮,但对我来说效果更好:

import android.content.res.Resources;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.ColorFilter;
import android.graphics.Paint;
import android.graphics.Paint.Align;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.util.TypedValue;

public class TextDrawable extends Drawable {
    private static final int DEFAULT_COLOR = Color.WHITE;
    private static final int DEFAULT_TEXTSIZE = 15;
    private Paint mPaint;
    private CharSequence mText;
    private int mIntrinsicWidth;
    private int mIntrinsicHeight;

    public TextDrawable(Resources res, CharSequence text) {
        mText = text;
        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mPaint.setColor(DEFAULT_COLOR);
        mPaint.setTextAlign(Align.CENTER);
        float textSize = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP,
                DEFAULT_TEXTSIZE, res.getDisplayMetrics());
        mPaint.setTextSize(textSize);
        mIntrinsicWidth = (int) (mPaint.measureText(mText, 0, mText.length()) + .5);
        mIntrinsicHeight = mPaint.getFontMetricsInt(null);
    }
    @Override
    public void draw(Canvas canvas) {
        Rect bounds = getBounds();
        canvas.drawText(mText, 0, mText.length(),
                bounds.centerX(), bounds.centerY(), mPaint);
    }
    @Override
    public int getOpacity() {
        return mPaint.getAlpha();
    }
    @Override
    public int getIntrinsicWidth() {
        return mIntrinsicWidth;
    }
    @Override
    public int getIntrinsicHeight() {
        return mIntrinsicHeight;
    }
    @Override
    public void setAlpha(int alpha) {
        mPaint.setAlpha(alpha);
    }
    @Override
    public void setColorFilter(ColorFilter filter) {
        mPaint.setColorFilter(filter);
    }
}

#4

To answer the comments above regarding how to center the text:

要回答以上关于如何使文本居中的评论:

mPaint.textAlign = Align.CENTER
...
// Centering for mixed case letters
canvas.drawText(mText, 0, mText.length,
        bounds.centerX().toFloat(), bounds.centerY().toFloat() - ((mPaint.descent() + mPaint.ascent()) / 2), mPaint)

// Centering for all uppercase letters
canvas.drawText(mText, 0, mText.length,
            bounds.centerX().toFloat(), bounds.centerY().toFloat() - mPaint.ascent() / 2, mPaint)

#1