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POCreate a transparent bitmap and UpdateLayeredWindow
 

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  1. POCreate a transparent bitmap and UpdateLayeredWindow
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    <p>I'm trying to create a mask window with "loading" text, to alert the user about a busy state of my application.</p> <p>For this, I first created a single form with:</p> <ul> <li>BorderStyle = bsNone</li> <li>Color = clBlack</li> <li>AlphaBlend = True</li> <li>AlphaBlendValue = 180;</li> </ul> <p>As the second step, I want to create another Form, but this one will has dynamic content. I need to create a transparent bitmap with some status text and use the UpdateLayeredWindow to draw the window as the text.</p> <p>Take a look and my desired result:</p> <p><img src="https://i.stack.imgur.com/l69Eq.jpg" alt="enter image description here"></p> <p>Remember: the text will be different in some cases, like:</p> <ul> <li>Recalculating</li> <li>Loading resources</li> <li>Loading report</li> </ul> <p>That's the reason what I need a dynamic bitmap generation.</p> <p><strong>QUESTION</strong></p> <p>How can I create a transparent bitmap with text and use it on a form with UpdateLayeredWindow?</p> <p>I'm trying this, but without success ( to try the code put a Button5 and Label2 on a form):</p> <pre><code> procedure Inc(var p: pointer); begin p := Pointer(Integer(p) + 1); end; var s: string; frm: TForm; f: HFont; tx: HDC; bmp, old: HBITMAP; rc: TRect; h: BITMAPINFOHEADER; pvBits: Pointer; t: tagBITMAPINFO; x,y: integer; a, r, g, b: byte; sz: TSize; p: tpoint; BlendFunction: TBlendFunction; begin tx := CreateCompatibleDC(0); s := label2.Caption; f := SelectObject(tx, label2.Font.Handle); fillchar(rc, SizeOf(rc), 0); DrawText(tx, PChar(s), length(s), rc, DT_CALCRECT); fillchar(h, SizeOf(h), 0); pvBits := nil; h.biSize := SizeOf(h); h.biWidth := rc.Right - rc.Left; h.biHeight := rc.Bottom - rc.Top; h.biPlanes := 1; h.biBitCount := 32; h.biCompression := BI_RGB; FillChar(t, SizeOf(t), 0); t.bmiHeader := h; bmp := CreateDIBSection(tx, t, 0, pvBits, 0, 0); old := SelectObject(tx, bmp); if old &gt; 0 then begin SetTextColor(tx, $00FFFFFF); SetBkColor(tx, $00000000); SetBkMode(tx, TRANSPARENT); DrawText(tx, PChar(s), length(s), rc, DT_NOCLIP); r := GetRValue($FF); g := GetGValue($FF); b := GetBValue($FF); for x := 0 to h.biWidth-1 do for y := 0 to h.biHeight-1 do begin a := Byte(pvBits^); Inc(pvBits); Byte(pvBits^) := (b * a) shr 8; Inc(pvBits); Byte(pvBits^) := (g * a) shr 8; Inc(pvBits); Byte(pvBits^) := (r * a) shr 8; Inc(pvBits); Byte(pvBits^) := a; end; SelectObject(tx, old); end; SelectObject(tx, f); deleteDC(tx); sz.cx := h.biWidth; sz.cy := h.biHeight; p := Point(0,0); BlendFunction.BlendOp := AC_SRC_OVER; BlendFunction.BlendFlags := 0; BlendFunction.SourceConstantAlpha := 255; BlendFunction.AlphaFormat := AC_SRC_ALPHA; frm := TForm.CreateNew(self); frm.BorderStyle := bsNone; frm.Position := poOwnerFormCenter; frm.Show; UpdateLayeredWindow(frm.Handle, 0, nil, @sz, bmp, @p, 0, @BlendFunction, ULW_ALPHA); end; </code></pre>
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    1. USBeto Neto
    1. USBeto Neto
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    3. VO
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    1. COAnd your question is?
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      1. POCreate a transparent bitmap and UpdateLayeredWindow
      1. USEric Brown
    2. COEric: now it's ok?
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      1. USBeto Neto
    3. COI don't get it: why don't you use a TLable on the transparent form?
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      1. USkobik
 

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