Font Size Differences

[JFee]

So I am making a graphics editor for TV stuff.... besides the point.

So the user can create text fields, and they choose a font size. They line the text fields up by dragging around a label. When the final graphic is created however, the text is drawn onto an image using GDI+. I am using the same font size, same font, same positioning, but the GDI+ Font shows up much smaller. Does anyone know why this is happening?

If that wasn't clear then feel free to ask for clarification. It's a little tricky to explain.

[dbzfanatic]

Maybe GDI+ uses something like 25px when the GUI uses 25? I don't use GDI (as of yet) so I'm not sure but I bet you could do a bit of searching and do a bit of math to even things out.

[JFee]

Thanks for the fast reply.

GDI has options about scale when it comes to text, and I think I've done all of them, and they're all different. I just find it interesting if they're both using the same scale why it would be different.

[JFee]

So I just got a great idea... I opened up Photoshop, and GDIPlus is doing it correctly. So now I just need to find out what unit of measurement GUI controls use for text...

[JFee]

Bump. Does anyone know how the GUI labels work in regards to font size?

[weaponx]

Photoshop type is measure in points by default, you can change it to pixels through preferences. AutoIt is most likely pixels.

[JFee]

In my GDI code that writes the text, I changed the font scale from points (default) to pixels. It was still off a ton. I tried all of the scale options in GDI+ and they are all different than the GUI text.

[weaponx]

Well after looking at the help file it seems AutoIt uses the windows standard font unit, which is points.

[Zinthose]

Bump. Does anyone know how the GUI labels work in regards to font size?

Font sizes for controls are are measured in points which amounts to 1/72 inch.

To produce the same font size in GDI use a $iUnit size = to 3, which is also the default.

The following generates matching fonts

GUICtrlSetFont(-1, 9, 400, 0, "Arial")
_GDIPlus_FontCreate("Arial", 9, 0, 3)

Edited August 28, 2008 by Zinthose

[JFee]

Change $imagePath to be any image. I am using a 720x486 png that is pure transparency. Compare the window to the image. They are in the same relative position, and should be the same size.

expandcollapse popup

#include <GUIConstantsEx.au3>
#include <WindowsConstants.au3>
#include <GDIPlus.au3>

$ImagePath = @ScriptDir & "\includes\transTemplate.png"

GUICreate("Text", 200, 100)
GUISetState()
$label = GUICtrlCreateLabel("Test 123", 10, 10, 190, 90)
GUICtrlSetFont(-1, 20, 400, 0, "Arial")

_GDIPlus_Startup()

$hImage = _GDIPlus_ImageLoadFromFile($ImagePath)
$hGraphics = _GDIPlus_ImageGetGraphicsContext($hImage)

;$hFontFamily = _GDIPlus_FontFamilyCreate("Arial")
;$hFont = _GDIPlus_FontCreate($hFontFamily, 20, 0, 3)
;$hFormat = _GDIPlus_StringFormatCreate ()
;$tLayout = _GDIPlus_RectFCreate (10, 10, 0, 0)
;$aInfo = _GDIPlus_GraphicsMeasureString ($hGraphics, "Test 123", $hFont, $tLayout, $hFormat)
;$hBrush = _GDIPlus_BrushCreateSolid ("0xFF000000")
;_GDIPlus_GraphicsDrawStringEx($hGraphics, "Test 123", $hFont, $aInfo[0], $hFormat, $hBrush)
;_GDIPlus_ImageSaveToFile($hImage, "FontSize.bmp")


$gFontFamily = _GDIPlus_FontFamilyCreate("Arial");$tFont)
$gFont = _GDIPlus_FontCreate($gFontFamily, 20, 0, 3)
$gBrush = _GDIPlus_BrushCreateSolid("0xFF000000")
$gFormat = _GDIPlus_StringFormatCreate()
$gLayout = _GDIPlus_RectFCreate(10, 10)
$gInfo = _GDIPlus_GraphicsMeasureString($hGraphics, "Test 123", $gFont, $gLayout, $gFormat)
_GDIPlus_GraphicsDrawStringEx($hGraphics, "Test 123", $gFont, $gInfo[0], $gFormat, $gBrush)
MsgBox(1, "", _GDIPlus_ImageSaveToFile($hImage, "FontSize.png"))

_GDIPlus_Shutdown()

While 1
    $msg = GUIGetMsg()
    Switch $msg
        Case $GUI_EVENT_CLOSE
            Exit
    EndSwitch
WEnd

[JFee]

Oh no! I figured out what the problem is.... it is the Pixels Per Inch of the original image. If I set the PPI to 1000 the text gets huge. Is there any way to make the PPI of a PNG automatic?