BUG report: update text of shape changes the font size

[sergedc]

BUG report: update text of shape changes the font size

[jcoliz]

Yeah, this is troublesome. It also changes the font family name as well for me. The workaround I have found is to not change the textframe text, but rather change only the paragraph text. Then I just make sure there are as many paragraphs already in the source presentation that I'll need.

[jcoliz]

@ashahabov Are you interested in a PR with a failing test for this? https://github.com/jcoliz/ShapeCrawler/tree/issue/638-text-font-size

        [Test]
        [Explicit]
        [SlideShape("001.pptx", 1, "TextBox 3")]
        [SlideShape("001.pptx", 3, "Text Placeholder 3")]
        public void Text_Setter_doesnt_change_font_size(IShape shape)
        {
            // Arrange
            var expected = shape.TextFrame.Paragraphs[0].Portions[0].Font.Size;

            // Act
            shape.TextFrame.Text = "New text";

            // Assert
            shape.TextFrame.Paragraphs[0].Portions[0].Font.Size.Should().Be(expected,$"{shape.Name} text size has changed");
        }

What's interesting is that this test only fails for the "Text Placeholder 3" case. "Textbox 3" case passes.

[jcoliz]

There is some suspicious stuff going on in FontService.GetAdjustedFontSize.

At the top of the method:

        paint.TextSize = fontSize;

And then at the bottom:

        const int dpi = 96;
        var points = Math.Round(paint.TextSize * 72 / dpi, 0);
        return (int)points;

Ergo, text size is guaranteed to get a 25% cut, even if the wordWidth never hits the rect.Right.

[jcoliz]

I now think the problem is that FontService.GetAdjustedFontSize sets the SKPaint.TextSize (in pixels) directly to the font size )in points), without making a points-to-pixels conversion. Once the previous PR gets through, I'll submit this for review.