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dotnet drawing api : Drawing text to a Bitmap has horrible looking output
Hi,
You can use the following GDI+ methods to improve the output: Graphics::SetInterpolationMode Graphics::SetSmoothingMode Graphics::SetPixelOffsetMode You can use the GDI graphic drawing to create a bitmap image, then use the following APIs to produce an antialias effect: SetStretchBltMode() using HALFTONE StretchBlt() http://msdn.microsoft.com/library/default.asp?url=/library/en-us/gdicpp/GDIPlus/GDIPlusReference/Classes/GraphicsClass/GraphicsMethods/SetInterpolationMode.asp http://msdn.microsoft.com/library/default.asp?url=/library/en-us/gdicpp/GDIPlus/GDIPlusreference/classes/graphicsclass/graphicsmethods/setsmoothingmode.asp http://msdn.microsoft.com/library/default.asp?url=/library/en-us/gdicpp/GDIPlus/GDIPlusReference/Classes/GraphicsClass/GraphicsMethods/SetPixelOffsetMode.asp http://msdn.microsoft.com/library/default.asp?url=/library/en-us/gdi/bitmaps_6cth.asp http://msdn.microsoft.com/library/default.asp?url=/library/en-us/gdi/bitmaps_9cok.asp Hope these suggestions helps, Kellie.
Hi,
The GDI and the Win32 APIs such as ExtTextOut() does not provide any antialias/text smoothing, only GDI+ support font smoothing, you might want to use the following API to enable smoothing mode: SystemParametersInfo() using SPI_SETFONTSMOOTHING, SPI_SETFONTSMOOTHINGCONTRAST, SPI_SETFONTSMOOTHINGTYPE http://msdn.microsoft.com/library/default.asp?url=/library/en-us/sysinfo/base/systemparametersinfo.asp Kellie.
Thanks ever Vigilent Kellie ;-)
[quoted text, click to view] "Kellie Fitton" <KELLIEFITTON@YAHOO.COM> wrote in message news:1148792547.949589.31000@u72g2000cwu.googlegroups.com... > Hi, > > The GDI and the Win32 APIs such as ExtTextOut() does not provide > any antialias/text smoothing, only GDI+ support font smoothing, > you might want to use the following API to enable smoothing mode: > > SystemParametersInfo() using SPI_SETFONTSMOOTHING, > SPI_SETFONTSMOOTHINGCONTRAST, > SPI_SETFONTSMOOTHINGTYPE > > http://msdn.microsoft.com/library/default.asp?url=/library/en-us/sysinfo/base/systemparametersinfo.asp > > Kellie. >
Thanks for all your links!
Unfortunatly none them help me fix the quality of the output of DrawString() on a Bitmap. I did some more test and discovered that if I paint the Background of my Bitmap first, or use a 24bpp bitmap g.DrawString() yield much better result. However my problem lies mainly with GDI drawing (ExtTextOut) as it is the API I should use. After doing some more test I come to realize that, perhaps, a Bitmap's HDC doesn't support the same quality hint as the screen HDC. it's why CreateFont(... CLEARTYPE_QUALITY ...) doesn't work for the Bitmap HDC? (while CreateFont(... ANTIALIASED_QUALITY ...) does) Do you have any tip on how to test, wether or not, the current device support the given font quality hint? So that I could gracefully drop one level?
I solved it!
In my MC++ wrapper around HDC, when it's created from a Bitmap, I maximize the Font quality to ANTIALIASED_QUALITY and it all works nicely :-)
disregard the previous post ..
grmrmbll...... still don't work.. sigh....
I tryed to do a bitmap export in my app by creating a bitmap, drawing to it
and saving the file. Something like that void SaveToFile(string pngfile) { using(Bitmap bmp = new Bitmap(200, 200); { using(Graphics g = Graphics.FromImage(bmp)) g.DrawString("Hello!", this.Font, Brushes.Black, 0, 50); bmp.Save(pngfile, ImageFormat.Png); } } But while this work, the resulting Bitmap, I mean the text quality on the Bitmap is appaling. Whatever the SmoothingMode or TextRenderingHit I use. Any tips to improve that? Also, in fact, I'm doing a lot of GDI drawing, and the text output with HDC / ExtTextOut suffer from the same problem, whatever quality hint I used in CreatFont(), any other GDI hint?
Standard Win32 CreateFont allows you to specify font-smoothing options with
no problem - certainly, I've never had any issue with creating a 'cleartype' font, and then drawing with this font to an off-screen DC - font smoothing works as expected in this case. Not tried doing this from GDI+ -> normal GDI though. James -- Microsoft MVP - Windows SDK www.catch22.net Free Win32 Source and Tutorials [quoted text, click to view] "Lloyd Dupont" <net.galador@ld> wrote in message news:%23XhhrEigGHA.3916@TK2MSFTNGP04.phx.gbl... > Thanks ever Vigilent Kellie ;-) > > "Kellie Fitton" <KELLIEFITTON@YAHOO.COM> wrote in message > news:1148792547.949589.31000@u72g2000cwu.googlegroups.com... >> Hi, >> >> The GDI and the Win32 APIs such as ExtTextOut() does not provide >> any antialias/text smoothing, only GDI+ support font smoothing, >> you might want to use the following API to enable smoothing mode: >> >> SystemParametersInfo() using SPI_SETFONTSMOOTHING, >> SPI_SETFONTSMOOTHINGCONTRAST, >> SPI_SETFONTSMOOTHINGTYPE >> >> http://msdn.microsoft.com/library/default.asp?url=/library/en-us/sysinfo/base/systemparametersinfo.asp >> >> Kellie. >> > >
When drawing to an offscreen bitmap using GDI you need to use a
CompatibleDC. Bitmap bm = new Bitmap(width, height, ImageFormat.24bpp); Graphics g = Graphics.FromImage(bm); g.FillRect(width, height, Brushes.Color) HDC hdc = g.GetHdc(); HDC cDC = CreateCompatibleDC(hdc); HBitmap bmOriginal = SelectObject(cDC, bm.GetHBitmap()); DrawText(cDC, ....); BitBlt(hdc, 0, 0, width, height, cDC, 0, 0, SRCCOPY); SelectObject(cDC, bmOriginal); DeleteDC(cDC); .... -- Mick Doherty http://dotnetrix.co.uk/nothing.html [quoted text, click to view] "Lloyd Dupont" <net.galador@ld> wrote in message news:%23pX23ikgGHA.3984@TK2MSFTNGP02.phx.gbl... >> Standard Win32 CreateFont allows you to specify font-smoothing options >> with no problem - certainly, I've never had any issue with creating a >> 'cleartype' font, and then drawing with this font to an off-screen DC - >> font smoothing works as expected in this case. Not tried doing this from >> GDI+ -> normal GDI though. >> > I think that's the issue. > Here is a simple weird test I have done. > > I create HFONT with CreateFont(... CLEARTYPE_QUALITY ..) > I also SetMapMode(MM_TEXT) and SetWorldTransform(rotated and scaled world) > > If I do > Image img = new Bitmap(width, height, ImageFormat.24bpp); <<== GDI work > better with 24bpp > HDC hdc = Graphics.FromImage(img).GetHdc(); > DrawText(hdc, ....) > > this produce nice text output, however if I do > > Image img = new Bitmap(width, height, ImageFormat.24bpp); > Graphics g = Graphics.FromImage(img); > g.FillRect(widt, height, Brushes.Color) <<=== new > HDC hdc = g.GetHdc(); > DrawText(hdc, ....) > > the text is blurred ... :-( > > Somehow some GDI+ operation have bad impact on my output. > And I can't removethe g.FillRect() as I have huge recursive mixed GDI/GDI+ > code .... > > However If I use CreateFont(.. ANTIALIAS_QUALITY ..) it works (I do get > the ANTIALIAS quality, not as nice as CLEARTYPE, but NOT blurred!) > >
[quoted text, click to view] "Lloyd Dupont" <net.galador@ld> wrote in message news:O0I%23EhmgGHA.4304@TK2MSFTNGP05.phx.gbl... >I tried that, which seems reasonable though a tad acrobatic but, quite >strangely, I had no GDI output at all when doing that ?!?! > Sounds like you either missed out the BitBlt, or the SelectObject afterwards. I am currently doing something very similar (in VB.Net though) and it works exactly as expected. [quoted text, click to view] > Anyway, I dropped this issue as it is quite marginal and I could make sure > to use ANTIALIAS_QUALITY in such case. > Personally I always like to know why something didn't work, even if I have an acceptable workaround. So in case it helps here are the exact methods that I am using along with an example of their usage: (Interop declarations not included) \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ 'You sometimes need to use GDI since the control whos surface 'you're drawing to uses GDI to measure the rectangle and the GDI+ 'DrawString method results in a string that's too long to fit. Private Sub DrawGDIText(ByVal hdc As IntPtr, ByVal text As String, _ ByVal font As Font, ByVal bounds As Rectangle, _ ByVal backColor As Color, _ ByVal foreColor As Color, _ ByVal alignment As ContentAlignment) SetTextColor(hdc, ColorTranslator.ToWin32(foreColor)) If backColor.Equals(Color.Transparent) Then SetBkMode(hdc, TRANSPARENT) Else SetBkMode(hdc, OPAQUE) SetBkColor(hdc, ColorTranslator.ToWin32(backColor)) End If Dim hFont As IntPtr = font.ToHfont Dim hOldFont As IntPtr = SelectObject(hdc, hFont) Dim flags As Int32 = DT_SINGLELINE Select Case alignment Case ContentAlignment.TopLeft flags += DT_TOP Or DT_LEFT Case ContentAlignment.TopCenter flags += DT_TOP Or DT_CENTER Case ContentAlignment.TopRight flags += DT_TOP Or DT_RIGHT Case ContentAlignment.MiddleLeft flags += DT_VCENTER Or DT_LEFT Case ContentAlignment.MiddleCenter flags += DT_VCENTER Or DT_CENTER Case ContentAlignment.MiddleRight flags += DT_VCENTER Or DT_RIGHT Case ContentAlignment.BottomLeft flags += DT_BOTTOM Or DT_LEFT Case ContentAlignment.BottomCenter flags += DT_BOTTOM Or DT_CENTER Case ContentAlignment.BottomRight flags += DT_BOTTOM Or DT_RIGHT End Select DrawText(hdc, text, -1, New RECT(bounds), flags) SelectObject(hdc, hOldFont) DeleteObject(hFont) End Sub 'A bitmap needs to pass a CompatibleDC to the DrawText method. Friend Sub DrawGDIText(ByVal bm As Bitmap, ByVal text As String, _ ByVal font As Font, ByVal bounds As Rectangle, _ ByVal backColor As Color, _ ByVal foreColor As Color, _ ByVal alignment As ContentAlignment) Dim g As Graphics = Graphics.FromImage(bm) If Not backColor.Equals(Color.Transparent) Then Dim backBrush As New SolidBrush(backColor) g.FillRectangle(backBrush, bounds) backBrush.Dispose() End If Dim hDC As IntPtr = g.GetHdc Dim cDC As IntPtr = CreateCompatibleDC(hDC) Dim hBitmap As IntPtr = SelectObject(cDC, bm.GetHbitmap) DrawGDIText(cDC, text, font, bounds, Color.Transparent, _ foreColor, alignment) BitBlt(hDC, bounds.Left, bounds.Top, bounds.Width, bounds.Height, _ cDC, bounds.Left, bounds.Top, SRCCOPY) SelectObject(cDC, hBitmap) DeleteDC(cDC) g.ReleaseHdc(hDC) g.Dispose() End Sub Private Sub Button1_Click(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles Button1.Click Dim bm As New Bitmap(someImage) Dim testFont As New Font("Times New Roman", 36, _ FontStyle.Italic, GraphicsUnit.Point) DrawGDIText(bm, "Sample", testFont, _ New Rectangle(Point.Empty, bm.Size), _ Color.FromArgb(200, 255, 128, 0), Color.White, _ ContentAlignment.MiddleCenter) testFont.Dispose() bm.Save("c:\Testing.png", Imaging.ImageFormat.Png) bm.Dispose() End Sub ///////////////////////////////////////////////////////////////////////////// [quoted text, click to view] > Regards, > Lloyd > > PS: I upgraded to the latest version of Nothing and it really works just > as expected! > Without all these annoying spywares and adwares you find in Anything > nowadays! > :-) I'll add that to my feedback -- Mick Doherty http://dotnetrix.co.uk/nothing.html
[quoted text, click to view]
> Standard Win32 CreateFont allows you to specify font-smoothing options I think that's the issue.> with no problem - certainly, I've never had any issue with creating a > 'cleartype' font, and then drawing with this font to an off-screen DC - > font smoothing works as expected in this case. Not tried doing this from > GDI+ -> normal GDI though. > Here is a simple weird test I have done. I create HFONT with CreateFont(... CLEARTYPE_QUALITY ..) I also SetMapMode(MM_TEXT) and SetWorldTransform(rotated and scaled world) If I do Image img = new Bitmap(width, height, ImageFormat.24bpp); <<== GDI work better with 24bpp HDC hdc = Graphics.FromImage(img).GetHdc(); DrawText(hdc, ....) this produce nice text output, however if I do Image img = new Bitmap(width, height, ImageFormat.24bpp); Graphics g = Graphics.FromImage(img); g.FillRect(widt, height, Brushes.Color) <<=== new HDC hdc = g.GetHdc(); DrawText(hdc, ....) the text is blurred ... :-( Somehow some GDI+ operation have bad impact on my output. And I can't removethe g.FillRect() as I have huge recursive mixed GDI/GDI+ code .... However If I use CreateFont(.. ANTIALIAS_QUALITY ..) it works (I do get the ANTIALIAS quality, not as nice as CLEARTYPE, but NOT blurred!)
I tried that, which seems reasonable though a tad acrobatic but, quite
strangely, I had no GDI output at all when doing that ?!?! Anyway, I dropped this issue as it is quite marginal and I could make sure to use ANTIALIAS_QUALITY in such case. Regards, Lloyd PS: I upgraded to the latest version of Nothing and it really works just as expected! Without all these annoying spywares and adwares you find in Anything nowadays! "Mick Doherty" <EXCHANGE#WITH@AND.REMOVE.SQUAREBRACKETS.[mdaudi100#ntlworld.com]> wrote in message news:%23ZRiWMlgGHA.3900@TK2MSFTNGP05.phx.gbl... [quoted text, click to view] > When drawing to an offscreen bitmap using GDI you need to use a > CompatibleDC. > > Bitmap bm = new Bitmap(width, height, ImageFormat.24bpp); > Graphics g = Graphics.FromImage(bm); > g.FillRect(width, height, Brushes.Color) > HDC hdc = g.GetHdc(); > > HDC cDC = CreateCompatibleDC(hdc); > HBitmap bmOriginal = SelectObject(cDC, bm.GetHBitmap()); > DrawText(cDC, ....); > BitBlt(hdc, 0, 0, width, height, cDC, 0, 0, SRCCOPY); > SelectObject(cDC, bmOriginal); > DeleteDC(cDC); > ... > > -- > Mick Doherty > http://dotnetrix.co.uk/nothing.html > > > "Lloyd Dupont" <net.galador@ld> wrote in message > news:%23pX23ikgGHA.3984@TK2MSFTNGP02.phx.gbl... >>> Standard Win32 CreateFont allows you to specify font-smoothing options >>> with no problem - certainly, I've never had any issue with creating a >>> 'cleartype' font, and then drawing with this font to an off-screen DC - >>> font smoothing works as expected in this case. Not tried doing this from >>> GDI+ -> normal GDI though. >>> >> I think that's the issue. >> Here is a simple weird test I have done. >> >> I create HFONT with CreateFont(... CLEARTYPE_QUALITY ..) >> I also SetMapMode(MM_TEXT) and SetWorldTransform(rotated and scaled >> world) >> >> If I do >> Image img = new Bitmap(width, height, ImageFormat.24bpp); <<== GDI work >> better with 24bpp >> HDC hdc = Graphics.FromImage(img).GetHdc(); >> DrawText(hdc, ....) >> >> this produce nice text output, however if I do >> >> Image img = new Bitmap(width, height, ImageFormat.24bpp); >> Graphics g = Graphics.FromImage(img); >> g.FillRect(widt, height, Brushes.Color) <<=== new >> HDC hdc = g.GetHdc(); >> DrawText(hdc, ....) >> >> the text is blurred ... :-( >> >> Somehow some GDI+ operation have bad impact on my output. >> And I can't removethe g.FillRect() as I have huge recursive mixed >> GDI/GDI+ code .... >> >> However If I use CreateFont(.. ANTIALIAS_QUALITY ..) it works (I do get >> the ANTIALIAS quality, not as nice as CLEARTYPE, but NOT blurred!) >> >> > >
[quoted text, click to view]
"Lloyd Dupont" <net.galador@ld> wrote in message news:uEmM2ufgGHA.1272@TK2MSFTNGP03.phx.gbl... > Thanks for all your links! > > Unfortunatly none them help me fix the quality of the output of > DrawString() on a Bitmap. > > I did some more test and discovered that if I paint the Background of my > Bitmap first, or use a 24bpp bitmap g.DrawString() yield much better > result. I accidentally replied to your previous post before reading this one. This statement confirms my suspicion concerning losing the alpha channel. When your bitmap has an alpha channel (32-bit), the GDI+ text routines use transparency to implement anti-aliasing. GDI doesn't understand the alpha channel information... it uses only grayscale blends with the background color. If you draw the background first, it's opaque and you get blends with the background with an opaque result. [quoted text, click to view] > > However my problem lies mainly with GDI drawing (ExtTextOut) as it is the > API I should use. > > After doing some more test I come to realize that, perhaps, a Bitmap's HDC > doesn't support the same quality hint as the screen HDC. > it's why CreateFont(... CLEARTYPE_QUALITY ...) doesn't work for the Bitmap > HDC? > (while CreateFont(... ANTIALIASED_QUALITY ...) does) > > Do you have any tip on how to test, wether or not, the current device > support the given font quality hint? > So that I could gracefully drop one level? >
Well I solved it.
Instead this, which would have required too many bitmap copy anyway (As I switch between GDI & GDI+ graphics all the time) I simply use the 'standart' double buffering class (BufferedGraphics, which seems to works well in windows forms) to draw to Bitmap too. And it worked! -- Regards, Lloyd Dupont NovaMind development team NovaMind Software Mind Mapping Software <www.nova-mind.com> "Mick Doherty" <EXCHANGE#WITH@AND.REMOVE.SQUAREBRACKETS.[mdaudi100#ntlworld.com]> wrote in message news:%23lEJ%23FogGHA.3916@TK2MSFTNGP04.phx.gbl... [quoted text, click to view] > > "Lloyd Dupont" <net.galador@ld> wrote in message > news:O0I%23EhmgGHA.4304@TK2MSFTNGP05.phx.gbl... >>I tried that, which seems reasonable though a tad acrobatic but, quite >>strangely, I had no GDI output at all when doing that ?!?! >> > > Sounds like you either missed out the BitBlt, or the SelectObject > afterwards. > > I am currently doing something very similar (in VB.Net though) and it > works exactly as expected. > >> Anyway, I dropped this issue as it is quite marginal and I could make >> sure to use ANTIALIAS_QUALITY in such case. >> > > Personally I always like to know why something didn't work, even if I have > an acceptable workaround. > So in case it helps here are the exact methods that I am using along with > an example of their usage: > (Interop declarations not included) > > \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ > 'You sometimes need to use GDI since the control whos surface > 'you're drawing to uses GDI to measure the rectangle and the GDI+ > 'DrawString method results in a string that's too long to fit. > Private Sub DrawGDIText(ByVal hdc As IntPtr, ByVal text As String, _ > ByVal font As Font, ByVal bounds As Rectangle, _ > ByVal backColor As Color, _ > ByVal foreColor As Color, _ > ByVal alignment As ContentAlignment) > > SetTextColor(hdc, ColorTranslator.ToWin32(foreColor)) > > If backColor.Equals(Color.Transparent) Then > SetBkMode(hdc, TRANSPARENT) > Else > SetBkMode(hdc, OPAQUE) > SetBkColor(hdc, ColorTranslator.ToWin32(backColor)) > End If > > Dim hFont As IntPtr = font.ToHfont > Dim hOldFont As IntPtr = SelectObject(hdc, hFont) > > Dim flags As Int32 = DT_SINGLELINE > Select Case alignment > Case ContentAlignment.TopLeft > flags += DT_TOP Or DT_LEFT > Case ContentAlignment.TopCenter > flags += DT_TOP Or DT_CENTER > Case ContentAlignment.TopRight > flags += DT_TOP Or DT_RIGHT > Case ContentAlignment.MiddleLeft > flags += DT_VCENTER Or DT_LEFT > Case ContentAlignment.MiddleCenter > flags += DT_VCENTER Or DT_CENTER > Case ContentAlignment.MiddleRight > flags += DT_VCENTER Or DT_RIGHT > Case ContentAlignment.BottomLeft > flags += DT_BOTTOM Or DT_LEFT > Case ContentAlignment.BottomCenter > flags += DT_BOTTOM Or DT_CENTER > Case ContentAlignment.BottomRight > flags += DT_BOTTOM Or DT_RIGHT > End Select > > DrawText(hdc, text, -1, New RECT(bounds), flags) > > SelectObject(hdc, hOldFont) > DeleteObject(hFont) > > End Sub > > 'A bitmap needs to pass a CompatibleDC to the DrawText method. > Friend Sub DrawGDIText(ByVal bm As Bitmap, ByVal text As String, _ > ByVal font As Font, ByVal bounds As Rectangle, _ > ByVal backColor As Color, _ > ByVal foreColor As Color, _ > ByVal alignment As ContentAlignment) > > Dim g As Graphics = Graphics.FromImage(bm) > > If Not backColor.Equals(Color.Transparent) Then > Dim backBrush As New SolidBrush(backColor) > g.FillRectangle(backBrush, bounds) > backBrush.Dispose() > End If > > Dim hDC As IntPtr = g.GetHdc > Dim cDC As IntPtr = CreateCompatibleDC(hDC) > Dim hBitmap As IntPtr = SelectObject(cDC, bm.GetHbitmap) > > DrawGDIText(cDC, text, font, bounds, Color.Transparent, _ > foreColor, alignment) > > BitBlt(hDC, bounds.Left, bounds.Top, bounds.Width, bounds.Height, _ > cDC, bounds.Left, bounds.Top, SRCCOPY) > > SelectObject(cDC, hBitmap) > DeleteDC(cDC) > > g.ReleaseHdc(hDC) > g.Dispose() > > End Sub > > Private Sub Button1_Click(ByVal sender As System.Object, _ > ByVal e As System.EventArgs) Handles Button1.Click > > Dim bm As New Bitmap(someImage) > > Dim testFont As New Font("Times New Roman", 36, _ > FontStyle.Italic, GraphicsUnit.Point) > > DrawGDIText(bm, "Sample", testFont, _ > New Rectangle(Point.Empty, bm.Size), _ > Color.FromArgb(200, 255, 128, 0), Color.White, _ > ContentAlignment.MiddleCenter) > > testFont.Dispose() > bm.Save("c:\Testing.png", Imaging.ImageFormat.Png) > bm.Dispose() > > End Sub > ///////////////////////////////////////////////////////////////////////////// > >> Regards, >> Lloyd >> >> PS: I upgraded to the latest version of Nothing and it really works just >> as expected! >> Without all these annoying spywares and adwares you find in Anything >> nowadays! >> > > :-) I'll add that to my feedback > > -- > Mick Doherty > http://dotnetrix.co.uk/nothing.html >
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