在DrawingContext中以角度绘制文本？

Question

以下是我使用的代码，用于获取现有图片、来自输入表单的文本，然后将来自输入表单的文本放置在现有图片上，并将其保存为新图片:

using (FileStream output = new FileStream(match_outputFile, FileMode.Create))
{
    BitmapImage bitmap = new BitmapImage(new Uri(match_sourceFile, UriKind.Relative));
    DrawingVisual visual = new DrawingVisual();

    using (DrawingContext image = visual.RenderOpen())
    {
        image.DrawImage(bitmap, new Rect(0, 0, bitmap.PixelWidth, bitmap.PixelHeight));

        buildText(image, "text1", this.text1.Text);
        buildText(image, "text2", this.text2.Text);
        buildText(image, "text3", this.text3.Text);
    }

    RenderTargetBitmap target = new RenderTargetBitmap(bitmap.PixelWidth, bitmap.PixelHeight, bitmap.DpiX, bitmap.DpiY, PixelFormats.Default);
    target.Render(visual);

    BitmapEncoder encoder = new PngBitmapEncoder();
    encoder.Frames.Add(BitmapFrame.Create(target));
    encoder.Save(output);
}

正如您所看到的，它调用以下函数来绘制文本：

private void buildText(DrawingContext image, string settings, string input)
{
    string[] setting = (Properties.Settings.Default[settings].ToString()).Split(',');

    FormattedText text = new FormattedText(
        input,
        System.Globalization.CultureInfo.InvariantCulture,
        FlowDirection.LeftToRight,
        new Typeface(new FontFamily(setting[0]), FontStyles.Normal, FontWeights.Bold, FontStretches.Normal),
        Convert.ToDouble(setting[5]),
        (Brush) new BrushConverter().ConvertFromString(setting[4])
    );
    text.MaxTextWidth = Convert.ToDouble(setting[8]);
    text.MaxTextHeight = Convert.ToDouble(setting[9]);

    Point position = new Point(Convert.ToDouble(setting[7]), Convert.ToDouble(setting[6]));

    switch (setting[2])
    {
        case "center": position.X += (Convert.ToDouble(setting[8]) - text.Width) / 2; break;
        case "right": position.X += Convert.ToDouble(setting[8]) - text.Width; break;
    }

    switch (setting[3])
    {
        case "middle": position.Y += (Convert.ToDouble(setting[9]) - text.Height) / 2; break;
        case "bottom": position.Y += Convert.ToDouble(setting[9]) - text.Height; break;
    }

    image.DrawText(text, position);
}

现在我需要的很简单...我需要将text2（且仅为text2）以中心位置为基准旋转一定角度后进行绘制。中心位置很简单，它应该是：

centerX = (setting[8] - setting[7]) / 2;
centerY = (setting[9] - setting[6]) / 2;

如果我想在中心位置以-30度的角度绘制此文本，怎么办？请记住，我只想旋转文本2，不是其他文本，也不是原始图像源。

- Jason Axelrod

Answer 1

在绘制文本之前，您可以简单地推送一个旋转变换到DrawingContext上。绘制后，弹出变换。

buildText(image, "text1", this.text1.Text);
image.PushTransform(new RotateTransform(angle, centerX, centerY));
buildText(image, "text2", this.text2.Text);
image.Pop();
buildText(image, "text3", this.text3.Text);

- Clemens