ios - 使用 MonoTouch.CoreText 绘制多行文本

Question

我用了那个例子 http://developer.xamarin.com/recipes/ios/graphics_and_drawing/core_text/draw_unicode_text_with_coretext/

Using MonoTouch.CoreText to draw text fragments at specific coordinaates

在 UIView 上绘制文本线。

现在我需要扩展它来绘制多行文本。基本上很简单。在 Draw() 方法中，我在“\n”上拆分多行字符串 Text，然后为任何向 Y 添加 newLineDY 的单行调用 DrawTextLine()。唯一的问题是任何新的线条绘制都会在前一条线条的 X 绘制结束之后开始:

啊啊啊 bbb 抄送

如何避免X位移？可以重置吗？如何？我尝试对任何行应用负 DX，但我不知道要应用的正确值。

private const float newLineDY = 40;
public override void Draw()
    {
        string[] lines = Text.Split("\n".ToCharArray());
        float lx = X;
        float ly = Y;
        foreach (string line in lines)
        {
            DrawTextLine(line, lx, ly);
            //lx -= 100;        // negative DX
            ly += newLineDY;
        }
    }
    private void DrawTextLine(string text, float x, float y)
    {
        CGContext gctx = UIGraphics.GetCurrentContext();
        gctx.SaveState();
        gctx.TranslateCTM(x, y);
        //gctx.TextPosition = new CGPoint(x, y);
        gctx.ScaleCTM(1, -1);
        //gctx.RotateCTM((float)Math.PI * 315 / 180);

        gctx.SetFillColor(UIColor.Black.CGColor);

        var attributedString = new NSAttributedString(text,
            new CTStringAttributes
            {
                ForegroundColorFromContext = true,
                Font = new CTFont("Arial", 24)
            });

        using (CTLine textLine = new CTLine(attributedString))
        {
            textLine.Draw(gctx);
        }
        gctx.RestoreState();
    }

谢谢!

Answer 1

我已经使用 attributedString.DrawString(new CGPoint(x, y)) 解决了问题，这是一个更简单的 API，如此处所建议的那样

http://monotouch.2284126.n4.nabble.com/Using-MonoTouch-CoreText-to-draw-text-fragments-at-specific-coordinates-td4658531.html

所以我的代码变成了:

    private const float newLineDY = 40;
    public override void Draw()
    {
        string[] lines = Text.Split("\n".ToCharArray());
        float lx = X;
        float ly = Y;
        foreach (string line in lines)
        {
            DrawTextLine(line, lx, ly);
            ly += newLineDY;
        }
    }
    private void DrawTextLine(string text, float x, float y)
    {
        NSAttributedString attributedString = new NSAttributedString(
            text,
            new CTStringAttributes
            {
                ForegroundColorFromContext = true,
                Font = new CTFont("Arial", 24)
            });
        attributedString.DrawString(new CGPoint(x, y));
    }