I have made these functions and so far for all png images it seems to work, but with the jpg I have found a few images where it shows the sizes divided by 10 and I have not figured out why yet. But its a start and perhaps someone can improve on it.
Local width:Int = 0
Local height:Int = 0
imageWidthHeightPNG("5.png",width,height)
Print Hex(width)+","+width
Print Hex(height)+","+height
imageWidthHeightJPG("5.jpg",width,height)
Print Hex(width)+","+width
Print Hex(height)+","+height
End
Function imageWidthHeightPNG(imagePath:String,width:Int Var, height:Int Var)
Local file:TStream = OpenStream(imagePath)
If ReadShort(file) <> $5089 Then Return False ' not a png image file
SeekStream(file,18)
width = ReadByte(file)*256
width :+ ReadByte(file)
SeekStream(file,22)
height = ReadByte(file)*256
height :+ ReadByte(file)
CloseStream(file)
End Function
Function imageWidthHeightJPG(imagePath:String,width:Int Var, height:Int Var)
Local file:TStream = OpenStream(imagePath)
If ReadShort(file) <> $D8FF Then Return False ' not a jpg image file
Local b1:Byte,b2:Byte,test:Byte=$E1
Local jump:Int
While Not Eof(file)
' locate jump instructions
Repeat
b1 = ReadByte(file)
Until b1 = $FF
b2 = ReadByte(file)
If b2 > $E0 And b2 < $EE Then ' jump instruction found
jump = ReadByte(file)*256+ReadByte(file)
SeekStream(file,StreamPos(file)+jump-2)
End If
If b2 = $EE Then ' no more jumps
' find width & height info
Repeat
b1 = ReadByte(file)
If b1 = $FF Then b2 = ReadByte(file)
Until (b1 = $FF And b2 = $C0) Or (b1 = $FF And b2 = $C1) Or (b1 = $FF And b2 = $C2) Or (b1 = $FF And b2 = $C3)
' skip 3 bytes
SeekStream(file,StreamPos(file)+3)
height = ReadByte(file)*256
height :+ ReadByte(file)
width = ReadByte(file)*256
width :+ ReadByte(file)
CloseFile(file)
Return
End If
Wend
End Function
[edit] I think that I figured out the jpg function. Some jpg files has embedded thumbnail images, and those need to be jumped past to get to the info of the actual image. So far I have not found any jpg images the above function cannot handle.
| 
