Android 在图像上绘制文本

我正在尝试使用以下代码在图像上绘制文本：

procedure TfMain.TextToImage(const AText: string; const AImage: TImage);
begin
  if NOT Assigned(AImage) then Exit;    
  AImage.Canvas.BeginScene;
  AImage.Canvas.Font.Size    := 18;
  AImage.Canvas.Font.Family  := 'Arial';
  AImage.Canvas.Fill.Color   := TAlphaColorRec.Dodgerblue;
  AImage.Canvas.Font.Style   := [TFontStyle.fsbold];
  AImage.Canvas.FillText( AImage.AbsoluteRect,
                          AText,
                          False,
                          1,
                          [TFillTextFlag.RightToLeft],
                          TTextAlign.taCenter,
                          TTextAlign.taCenter);
  AImage.Canvas.EndScene;
end;

---

问：为什么上面的程序在Windows上工作，而在android上不工作？

请参见下面的自定义类，了解android中文本的

ImageView

。但是需要使用TTF或OTF文件来获取更多的文本

package com.fuzzydev;

import com.fuzzydev.labeledimageview.R;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Typeface;
import android.util.AttributeSet;
import android.util.Log;
import android.widget.ImageView;

/*
 * ----------------------------------------------------------------------------
 * "THE BEER-WARE LICENSE" (Revision 42):
 * As long as you retain this notice you
 * can do whatever you want with this stuff. If we meet some day, and you think
 * this stuff is worth it, you can buy me a beer in return Dejan Ristic
 * ----------------------------------------------------------------------------
 */

public class LabeledImageView extends ImageView {

    private static final String TAG = "LabeledImageView";

    private static final int DEFAULT_TEXT_STYLE = Typeface.NORMAL;
    private static final int DEFAULT_TEXT_COLOR = Color.WHITE;
    private static final int DEFAULT_SCREEN_LOCATION = 0;
    private static final int DEFAULT_X_OFFSET = 30;
    private static final int DEFAULT_Y_OFFSET = 30;

    private static final float DEFAULT_TEXT_SIZE = 40f;

    private float textSize;
    private float xPos, yPos;
    private float xOffset, yOffset;

    private int labelLocation;
    private int textStyle;
    private int textColor;

    private String text;
    private String customFont;

    private Paint mTextPaint;

    public LabeledImageView(Context context) {
        super(context);
        initWithDefautls();
    }

    public LabeledImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
        initWithAttrs(attrs, context);
    }

    private void initWithDefautls() {
        textSize = DEFAULT_TEXT_SIZE;
        textStyle = DEFAULT_TEXT_STYLE;
        textColor = DEFAULT_TEXT_COLOR;
        labelLocation = DEFAULT_SCREEN_LOCATION;
        xOffset = DEFAULT_X_OFFSET;
        yOffset = DEFAULT_Y_OFFSET;
        setTextPaint();
    }

    private void initWithAttrs(AttributeSet attrs, Context context) {
        initAttrs(context, attrs);
        setTextPaint();
        if (customFont != null) {
            setCustomFont(context);
        }
    }

    private void initAttrs(Context context, AttributeSet attrs) {
        TypedArray a = context.getTheme().obtainStyledAttributes(attrs,
                R.styleable.LabeledImageView, 0, 0);

        try {
            text = a.getString(R.styleable.LabeledImageView_text);
            textSize = a.getFloat(R.styleable.LabeledImageView_textSizePx,
                    DEFAULT_TEXT_SIZE);
            textStyle = a.getInt(R.styleable.LabeledImageView_textStyle,
                    DEFAULT_TEXT_STYLE);
            textColor = a.getInt(R.styleable.LabeledImageView_textColor,
                    DEFAULT_TEXT_COLOR);
            labelLocation = a.getInt(
                    R.styleable.LabeledImageView_labelPosition,
                    DEFAULT_SCREEN_LOCATION);
            customFont = a.getString(R.styleable.LabeledImageView_customFont);
            xOffset = a.getFloat(R.styleable.LabeledImageView_xOffset,
                    DEFAULT_X_OFFSET);
            yOffset = a.getFloat(R.styleable.LabeledImageView_yOffset,
                    DEFAULT_Y_OFFSET);
            ;
        } finally {
            a.recycle();
        }
    }

    private void setCustomFont(Context ctx) {
        Typeface tf = null;
        try {
            tf = Typeface.createFromAsset(ctx.getAssets(), customFont);
        } catch (Exception e) {
            Log.e(TAG, "Could not get typeface: " + e.getMessage());
        }
        mTextPaint.setTypeface(tf);
    }

    private void setLabelLocation() {

        switch (labelLocation) {
        case 0: // Top Left
            xPos = xOffset;
            yPos = yOffset;
            break;
        case 1: // Top Right
            xPos = getWidth() - mTextPaint.measureText(text) - xOffset;
            yPos = yOffset;
            break;
        case 2: // Bottom Left
            xPos = xOffset;
            yPos = getHeight() - yOffset;
            break;
        case 3: // Bottom Right
            xPos = getWidth() - mTextPaint.measureText(text) - xOffset;
            yPos = getHeight() - yOffset;
            break;
        case 4: // Top Center
            xPos = (getWidth() / 2) - (mTextPaint.measureText(text) / 2);
            yPos = yOffset;
            break;
        case 5: // Bottom Center
            xPos = (getWidth() / 2) - (mTextPaint.measureText(text) / 2);
            yPos = getHeight() - yOffset;
            break;
        case 6: // Center
            xPos = (getWidth() / 2) - (mTextPaint.measureText(text) / 2);
            yPos = (getHeight() / 2);
        default:
            break;
        }
    }

    @Override
    public void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        setLabelLocation();
    }

    private void setTextPaint() {
        mTextPaint = new Paint();
        mTextPaint.setTextSize(textSize);
        mTextPaint.setColor(textColor);
        mTextPaint.setTypeface(Typeface.defaultFromStyle(textStyle));
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if (text != null) {
            canvas.drawText(text, xPos, yPos, mTextPaint);
        }
    }

    public void setTextSize(float textSize) {
        this.textSize = textSize;
    }

    public void setCustomFont(String customFont) {
        this.customFont = customFont;
    }

    public void setLabelLocation(int labelLocation) {
        this.labelLocation = labelLocation;
    }

    public void setyOffset(float yOffset) {
        this.yOffset = yOffset;
    }

    public void setxOffset(float xOffset) {
        this.xOffset = xOffset;
    }

    public String getText() {
        return text;
    }

    public void setText(String text) {
        this.text = text;
    }

    public void setTextStyle(int textStyle) {
        this.textStyle = textStyle;
    }

    public void setTextColor(int textColor) {
        this.textColor = textColor;
    }
}

请参见本文中上述类的实现

---

link

尝试直接在timage的

TBitmap

上绘制，而不是在timage的画布上绘制

在尝试访问图像之前，您还需要创建图像的位图：

AImage.Bitmap := TBitmap.Create(Round(AImage.Width), Round(AImage.Height));

因此，正确的代码如下所示：

procedure TfMain.TextToImage(const AText: string; const AImage: TImage);
begin
  if NOT Assigned(AImage) then Exit;
  AImage.Bitmap := TBitmap.Create(Round(AImage.Width), Round(AImage.Height));
  AImage.Bitmap.Canvas.BeginScene;
  try
    //....
    // Use AImage.Bitmap.Canvas as needed
    AImage.Bitmap.Canvas.FillText( AImage.AbsoluteRect,
                            AText,
                            False,
                            1,
                            [],
                            TTextAlign.Center,
                            TTextAlign.Center);
  finally
    AImage.Bitmap.Canvas.EndScene;
  end;
end;

从

TImage.Paint

事件代码中，您将看到：

procedure TImage.Paint;
var
  R: TRectF;
begin
  if (csDesigning in ComponentState) and not Locked and not FInPaintTo then
  begin
    R := LocalRect;
    InflateRect(R, -0.5, -0.5);
    Canvas.DrawDashRect(R, 0, 0, AllCorners, AbsoluteOpacity, $A0909090);
  end;

  UpdateCurrentBitmap;
  if FCurrentBitmap <> nil then
    DrawBitmap(Canvas, LocalRect, FCurrentBitmap, AbsoluteOpacity);
end;

程序TImage.Paint；
变量
R:TRectF；
开始
如果（csDesigning in ComponentState）未锁定且未找到，则
开始
R:=LocalRect；
充气（R，-0.5，-0.5）；
DrawDashRect（R，0，0，所有角，绝对不透明度，$A0909090）；
结束；
更新当前位图；
如果FCurrentBitmap为零，则
DrawBitmap（画布、LocalRect、FCurrentBitmap、绝对不透明度）；
结束；

因此，无论您将在画布上绘制什么，在下一次重新绘制时，它将再次绘制完整的位图，删除您已经完成的操作

---

如果不想触摸位图，则需要覆盖

TImage

的

OnPaint

事件，并调用

函数TextToImage（const-AText:string；const-AImage:TImage）

你确定

android

标签贴得合适吗？@azizbekian我想是的，你看过我的Q了吗？或者你只是看了一下代码：）在Android中，我们可以通过自定义视图来实现这一点，我们需要添加所有TTF文件，这些文件需要应用到Android中的文本中。这看起来像Delphi代码吗？这个问题显然被标记为Delphi，因此Java解决方案并没有多大帮助。