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Program startup: performance improvements on cold start
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GDI+ font rendering is out.  My previous workarounds for faster GDI+ font creation proved unreliable.  The testing matrix of GDI+ against various Windows versions (let alone redist possibilities, which I haven't been testing) is simply too large for me to make concrete perf decisions, especially since there are hidden changes on Win 10 (to explain why GDI+ can suddenly handle OpenType fonts).  PD's startup perf performance is extremely sensitive to random lags when the GDI+ font renderer decides it needs to cache enormous chunks of data, so rather than try and fix it, I'm just gonna revert to GDI fonts.

Across all OS versions, it's more code - but much faster - to simply use a GDI font on a 24-bpp surface, then manually upsample to 32-bpp and paint that onto our screen overlay.  This removes variability and while it's a little ugly (and the font aliasing is not as good), it's "good enough" for a splash screen, and it removes the potential for random lags at startup.
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@tannerhelland
tannerhelland committed Dec 18, 2020
1 parent ac2772d commit a56af48
Showing 1 changed file with 40 additions and 89 deletions.
129 changes: 40 additions & 89 deletions Forms/Startup_Splash.frm
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Original file line number Diff line number Diff line change
Expand Up @@ -42,8 +42,10 @@ Attribute VB_Exposed = False
'PhotoDemon Splash Screen
'Copyright 2001-2020 by Tanner Helland
'Created: 15/April/01
'Last updated: 10/June/20
'Last update: rewrite as a proper layered window with alpha effects
'Last updated: 18/December/20
'Last update: remove GDI+ font code from splash rendering; GDI+ font creation functions have
' unpredictable perf impacts, and it's reliably faster to use GDI on 24-bpp surfaces
' (then produce a 32-bpp copy ourselves)
'
'Unless otherwise noted, all source code in this file is shared under a simplified BSD license.
' Full license details are available in the LICENSE.md file, or at https://photodemon.org/license/
Expand All @@ -57,20 +59,6 @@ Private Declare Function GetWindowRect Lib "user32" (ByVal hWnd As Long, ByRef l
Private Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
Private Declare Function UpdateLayeredWindow Lib "user32" (ByVal hWnd As Long, ByVal hdcDst As Long, ByVal pptDst As Long, ByVal psize As Long, ByVal hdcSrc As Long, ByVal pptSrc As Long, ByVal crKey As Long, ByVal pblend As Long, ByVal dwFlags As Long) As Long

'Unfortunately, GDI doesn't render text onto 32-bpp surfaces correctly (the alpha channel gets ignored).
' We need to use a more convoluted GDI+ approach, and because I don't have a safe wrapper class for
' GDI+ font rendering, everything gets called manually.
'Private Declare Function GdipCreateFont Lib "gdiplus" (ByVal srcFontFamily As Long, ByVal srcFontSize As Single, ByVal srcFontStyle As Long, ByVal srcMeasurementUnit As Long, ByRef dstCreatedFont As Long) As GP_Result
'Private Declare Function GdipCreateFontFamilyFromName Lib "gdiplus" (ByVal ptrToSrcFontName As Long, ByVal srcFontCollection As Long, ByRef dstFontFamily As Long) As GP_Result
Private Declare Function GdipCreateFontFromDC Lib "gdiplus" (ByVal srcDC As Long, ByRef dstCreatedFont As Long) As GP_Result
Private Declare Function GdipCreateStringFormat Lib "gdiplus" (ByVal formatAttributes As Long, ByVal srcLanguage As Long, ByRef dstStringFormat As Long) As GP_Result
Private Declare Function GdipDeleteFont Lib "gdiplus" (ByVal srcFont As Long) As GP_Result
'Private Declare Function GdipDeleteFontFamily Lib "gdiplus" (ByVal srcFontFamily As Long) As GP_Result
Private Declare Function GdipDeleteStringFormat Lib "gdiplus" (ByVal srcStringFormat As Long) As GP_Result
Private Declare Function GdipDrawString Lib "gdiplus" (ByVal dstGraphics As Long, ByVal srcStringPtr As Long, ByVal strLength As Long, ByVal gdipFontHandle As Long, ByRef layoutRect As RectF, ByVal gdipStringFormat As Long, ByVal gdipBrush As Long) As GP_Result
Private Declare Function GdipSetStringFormatAlign Lib "gdiplus" (ByVal dstStringFormat As Long, ByVal newAlignment As Long) As GP_Result
Private Declare Function GdipSetTextRenderingHint Lib "gdiplus" (ByVal dstGraphics As Long, ByVal newRenderHintMode As Long) As GP_Result

'A logo, drop shadow and screen backdrop are used to generate the splash. These DIBs are released once m_splashDIB (below)
' has been successfully assembled.
Private m_logoDIB As pdDIB, m_shadowDIB As pdDIB
Expand Down Expand Up @@ -162,92 +150,55 @@ Public Sub PrepareRestOfSplash()
Dim logoFontName As String
If OS.IsVistaOrLater Then logoFontName = "Segoe UI" Else logoFontName = "Tahoma"

'Next, we need to create various GDI+ font objects. These may fail (particularly on
' non-standard configs like Wine), so abandon font rendering if anything goes badly.
Dim fontOK As Boolean, gpFontHandle As Long

'YIKES! For ages I have used the normal GDI+ pathway of GdipCreateFontFamily > GdipCreateFont,
' but after experiencing random startup stutters on Win 10, I profiled and tracked down the
' CreateFontFamily call as the culprit. It occasionally takes hundreds of ms, with occasional
' lurches above ONE SECOND for that single function call! I have no idea when this changed,
' but I've got a reliable workaround - turns out it's much much MUCH faster (e.g. < 10 ms vs
' 500+ ms) to initialize a GDI font, attach it to a GDI DC, then indirectly create a GDI+ font
' from said DC. Go figure.

'Original code here in case I ever need to revert this approach:
'Dim gpFontFamily As Long
'fontOK = (GdipCreateFontFamilyFromName(StrPtr(logoFontName), 0&, gpFontFamily) = GP_OK)
'Const GP_FONTBOLD As Long = 1
'If fontOK Then fontOK = (GdipCreateFont(gpFontFamily, logoFontSize, GP_FONTBOLD, GP_U_Point, gpFontHandle) = GP_OK)
'Font color varies by build version.
' (As a convenience, non-production builds are tagged RED; normal builds, BLUE.)
Dim logoFontColor As Long
If (PD_BUILD_QUALITY <> PD_PRODUCTION) Then logoFontColor = RGB(255, 50, 50) Else logoFontColor = RGB(50, 127, 255)

'New approach: use pdFont to create a font, because it's ~50x faster!
'Create a GDI font with the desired settings
Dim tmpFont As pdFont
Set tmpFont = New pdFont
tmpFont.SetFontFace logoFontName
tmpFont.SetFontSize logoFontSize
tmpFont.SetFontBold True
tmpFont.CreateFontObject
tmpFont.AttachToDC m_splashDIB.GetDIBDC
fontOK = (GdipCreateFontFromDC(m_splashDIB.GetDIBDC, gpFontHandle) = GP_OK)

'Kill the temporary GDI font copy
'Assemble the current version and description strings
Dim versionString As String
versionString = Trim$(g_Language.TranslateMessage("version %1", Updates.GetPhotoDemonVersion()))

'Create a dummy 24-bpp DIB and paint the version to it. (This is required for reliable
' antialiasing behavior; GDI can't render text to 32-bpp surfaces if antialiasing is active,
' so we need to paitn to a 24-bpp surface, then upsample to 32-bpp and fill in alpha manually.)
Dim fntWidth As Long, fntHeight As Long
fntWidth = tmpFont.GetWidthOfString(versionString)
fntHeight = tmpFont.GetHeightOfString(versionString)

'Create a temporary 24-bpp target for the text. (We'll use white-on-black text to
' simplify the process of manually upsampling to 32-bpp.)
Dim tmpDIB As pdDIB
Set tmpDIB = New pdDIB
tmpDIB.CreateBlank fntWidth, fntHeight, 24, vbBlack

'Paint the version string
tmpFont.SetFontColor vbWhite
tmpFont.AttachToDC tmpDIB.GetDIBDC
tmpFont.FastRenderText 0, 0, versionString
tmpFont.ReleaseFromDC
Set tmpFont = Nothing

'Next, we need a text formatter. Minimal options are used, but we do need right-alignment
Dim gpStringFormat As Long
If fontOK Then fontOK = (GdipCreateStringFormat(0&, 0&, gpStringFormat) = GP_OK)

Const GP_STRINGALIGNFAR As Long = 2
If fontOK Then fontOK = (GdipSetStringFormatAlign(gpStringFormat, GP_STRINGALIGNFAR) = GP_OK)

'Everything else uses prebuilt PD classes
Dim cSurface As pd2DSurface, cBrush As pd2DBrush
'Convert the temporary DIB to 32-bpp, using the grayscale channel as the alpha guide
tmpDIB.ConvertTo32bpp
Dim grayArray() As Byte
ReDim grayArray(0 To fntWidth - 1, 0 To fntHeight - 1) As Byte
DIBs.GetDIBGrayscaleMap tmpDIB, grayArray, False

'If we created everything correctly, render version text
If fontOK And (m_splashDIB.GetDIBDC <> 0) Then

'Next, we need a layout rect
Dim fontRect As RectF
fontRect.Top = pdLogoBottom + Interface.FixDPI(8)
fontRect.Left = 0
fontRect.Width = pdLogoRight
fontRect.Height = fontRect.Top + 100

'Assemble the current version and description strings
Dim versionString As String
versionString = Trim$(g_Language.TranslateMessage("version %1", Updates.GetPhotoDemonVersion()))

'Wrap a GDI+ surface around the destination DIB
Set cSurface = New pd2DSurface
cSurface.WrapSurfaceAroundPDDIB m_splashDIB

'Activate grayscale antialiasing + hinting
Const GP_TextRenderingHintAntiAliasGridFit As Long = 3
GdipSetTextRenderingHint cSurface.GetHandle, GP_TextRenderingHintAntiAliasGridFit

'Next, font color.
' (As a convenience, non-production builds are tagged RED; normal builds, BLUE.)
Dim logoFontColor As Long
If (PD_BUILD_QUALITY <> PD_PRODUCTION) Then logoFontColor = RGB(255, 50, 50) Else logoFontColor = RGB(50, 127, 255)

'Text gets painted by a stock GDI+ brush
Set cBrush = New pd2DBrush
cBrush.SetBrushColor logoFontColor

'Render the finished text!
GdipDrawString cSurface.GetHandle, StrPtr(versionString), Len(versionString), gpFontHandle, fontRect, gpStringFormat, cBrush.GetHandle

End If

'Free various font and string objects
Set cBrush = Nothing
Set cSurface = Nothing
If (gpStringFormat <> 0) Then GdipDeleteStringFormat gpStringFormat
If (gpFontHandle <> 0) Then GdipDeleteFont gpFontHandle
tmpDIB.CreateBlank fntWidth, fntHeight, 32, logoFontColor, 255
DIBs.ApplyTransparencyTable tmpDIB, grayArray
tmpDIB.SetAlphaPremultiplication True

'A GDI+ font family object is no longer allocated; see above comments for details
'If (gpFontFamily <> 0) Then GdipDeleteFontFamily gpFontFamily
'Paint the final 32-bpp version image onto the splash screen
tmpDIB.AlphaBlendToDC m_splashDIB.GetDIBDC, dstX:=pdLogoRight - fntWidth, dstY:=pdLogoBottom + Interface.FixDPI(8)

'We now have a back buffer with everything the splash screen requires
' (except the progress bar, which will be drawn later). Create a front buffer
Expand Down

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