[Closed] DrawText with the correct alpha ?

Wait for it… Wait for it… Denis has a question!!!

(sorry Denis couldn’t resist)
:bowdown:

as far as I know it’s a limitation of text rendering in gdi. There’s no 8-bit alpha value in the resulting image, only a 1-bit transparency value. What’s wrong with post processing?

i swear i don’t have an answer.
i can use GDI+ with Graphics.DrawString. but i have the same result. The mask is shifted 1 px left against the text.

What do you mean? You do get an 8-bit alpha but it’s not in the right position? I get a 1-bit alpha both with textrenderer and drawstring.

i can explain what i want to achieve.
you probably saw when some custom controls do dragging of a content with semi-transparent bitmap
(devx controls for example). But most of them do it with ugly 1-bit transparensy bitmap. I want to make it better!

i have some better result… almost OK

fn waterMark txt font: fore: =
(
	temp = (dotNetClass "System.IO.Path").ChangeExtension ((dotNetClass "System.IO.Path").GetTempFileName()) "png"
	setclipboardtext temp
	
	if font == unsupplied do font = (dotnetclass "SystemInformation").MenuFont

	bm = dotnetobject "System.Drawing.Bitmap" 1 1
	global gr = (dotnetclass "System.Drawing.Graphics").FromImage bm
	
	sz = (gr.MeasureString txt font).ToSize()
	
	if fore == unsupplied do fore = (dotnetclass "System.Drawing.Color").Red
	back = (dotnetclass "System.Drawing.Color").Transparent
	
	bm = dotnetobject "System.Drawing.Bitmap" sz.width (font.GetHeight())
	global gr = (dotnetclass "System.Drawing.Graphics").FromImage bm

--	gr.CompositingMode = gr.CompositingMode.SourceOver
--	gr.CompositingQuality = gr.CompositingQuality.HighQuality
--	gr.SmoothingMode = gr.SmoothingMode.HighQuality
	gr.PixelOffsetMode = gr.PixelOffsetMode.HighQuality
	gr.TextRenderingHint = gr.TextRenderingHint.AntiAliasGridFit --ClearTypeGridFit 
		
	clip = dotnetobject "System.Drawing.Rectangle" 0 0 bm.width bm.height

	gr.Clear back
	gr.DrawString txt font (dotnetobject "System.Drawing.SolidBrush" fore) 0 0 
	gr.DrawImage bm (dotnetobject "System.Drawing.Rectangle" 0 0 bm.width bm.height)

--	bm.MakeTransparent back

	bm.Save temp (dotnetclass "System.Drawing.Imaging.ImageFormat").png
	
	gr.Dispose()
	bm.Dispose()
	
	bb = openbitmap temp
--	deletefile temp
	display bb
	bb
)

font = dotnetobject "System.Drawing.Font" "Tahoma" 14 (dotnetclass "System.Drawing.FontStyle").Regular
waterMark "Hey, World!" font:font

cool… why almost? what’s wrong with it.

also, what is the purpose of

gr.DrawImage bm (dotnetobject "System.Drawing.Rectangle" 0 0 bm.width bm.height)

you are drawing the image on itself?

Yes, always

In any case, what is wrong with the result you are getting? It looks ok to me

TextRenderingHint.ClearTypeGridFit is the highest quality setting. But it doesn’t work right for me…