OOP question

BlitzMax Forums/BlitzMax Beginners Area/OOP question

Ant
 #1
Hi there, a question on types and scope I guess. If I declare a type and in that type declare:

Field imgFont:TImage


Then in a method of the same type have the following:

imgFont= LoadAnimImage("font16p.png",16,16,0,..
126-32+1,DYNAMICIMAGE|MASKEDIMAGE)

will the contents of imgFont be available to other methods in that type? Doesnt seem to be...

Thanks for the help - a grateful newbie ;-)

FlameDuck
 #2
will the contents of imgFont be available to other methods in that type?
Yes, but not to functions. Got code?

Ant
 #3
Here it is.....

Strict
Graphics 640,480,0
HideMouse



Type TFont
Field iLastASCII=126
Field iFirstASCII=32

Field iCellWidth=16
Field iCellHeight=16

Field imgFont: TImage
Field iWidthTable[iLastASCII-iFirstASCII+1]

Method CreateFont(sFontName$)

Local iMaxWidth=0
Local i,x,y,alpha=0
'Local imgfont

SetMaskColor (255,0,255)
imgFont= LoadAnimImage("font16p.png",16,16,0,..
126-32+1,DYNAMICIMAGE|MASKEDIMAGE)





If Not imgfont Print "cant fin font"
For i=1 To (iLastASCII-iFirstASCII)

Local img=LockImage(imgFont,i)
For x=(iCellWidth-1) To 0 Step -1
For y=0 Until iCellHeight
alpha=ReadPixel(img,x,y) & $ff000000
If alpha Then Exit
Next
If alpha Then Exit
Next
UnlockImage imgFont,i
iWidthTable[i]=x+1
If x>iMaxWidth Then iMaxWidth=x
Next
iWidthTable[0]=iMaxWidth*.3

EndMethod


Method DrawBmpFont(text$,x,y)
Local i=0
For i=0 Until text.length
DrawImage imgFont,x,y,Asc(text[i..i+1])-32
x:+iWidthTable[Asc(text[i..i+1])-32]
Next
EndMethod
EndType

Local ArialFont:TFont
ArialFont = New TFont
ArialFont.iFirstASCII = 32
ArialFont.iLastASCII = 126

ArialFont.iCellWidth = 16
ArialFont.iCellHeight = 16

ArialFont.CreateFont("font16p.png")




While Not KeyDown(key_escape)
ArialFont.DrawBmpFont("Hello",100,100)
Flip
Cls

Wend


...basically I want to know if the DrawBmpFont method can access imgFont.
Thanks

FlameDuck
 #4
This works here (BlitzMAX 1.14), and isn't significantly different from your example:
Strict
Graphics 640,480,0

Type TFont
	Field iLastASCII=126
	Field iFirstASCII=32

	Field iCellWidth=16
	Field iCellHeight=16

	Field imgFont:TImage
	Field iWidthTable[iLastASCII-iFirstASCII+1]

	Method CreateFont(sFontName$)

		Local iMaxWidth=0
		Local i,x,y,alpha=0
		SetMaskColor (255,0,255)
		imgFont= LoadAnimImage(sFontName,16,16,0,..
		126-32+1,DYNAMICIMAGE|MASKEDIMAGE)

		If Not imgfont Print "can't find font"
		For i=1 To (iLastASCII-iFirstASCII)
			Local img:TPixmap=LockImage(imgFont,i)
			For x=(iCellWidth-1) To 0 Step -1
				For y=0 Until iCellHeight
					alpha=ReadPixel(img,x,y) & $ff000000
					If alpha Then Exit
				Next
				If alpha Then Exit
			Next
			UnlockImage imgFont,i
			iWidthTable[i]=x+1
			If x>iMaxWidth Then iMaxWidth=x
		Next
		iWidthTable[0]=iMaxWidth*.3
	EndMethod

	Method DrawBmpFont(text$,x,y)
		Local i=0
		For i=0 Until text.length
			DrawImage imgFont,x,y,Asc(text[i..i+1])-32
			x:+iWidthTable[Asc(text[i..i+1])-32]
		Next
	EndMethod
EndType

Local ArialFont:TFont
ArialFont = New TFont
ArialFont.iFirstASCII = 32
ArialFont.iLastASCII = 126

ArialFont.iCellWidth = 16
ArialFont.iCellHeight = 16

ArialFont.CreateFont("font16p.png")

While Not KeyDown(key_escape)
	ArialFont.DrawBmpFont("Hello",100,100)
	Flip
	Cls
Wend
The DrawBmpFont method can access imgFont just fine. Maybe your PNG file is corrupted or something?

Ant
 #5
I've got it working at the expense of getting very confused. The following code works:

*****************************************
Strict
Graphics 640,480,0
HideMouse



Type TFont
Field iLastASCII=126 'Local as it may need to be different for each font object
Field iFirstASCII=32 'Local as it may need to be different for each font object

Field iCellWidth
Field iCellHeight


Field imgFont: TImage ' Local as it needs to specific to each instance (each font)
Field iWidthTable[iLastASCII-iFirstASCII+1] ' Again, local

Method CreateFont(sFontName$) 'try it without the $ if there's a problem - check later

Local iMaxWidth=0
Local i,x,y,alpha=0


SetMaskColor (255,0,255)
imgFont= LoadAnimImage("font16p.png",16,16,0,..
126-32+1,DYNAMICIMAGE|MASKEDIMAGE)
If Not imgfont Print "Cant find font to load"



For i=1 To (iLastASCII-iFirstASCII) ' step through each character

Local img=LockImage(imgFont,i) ' lock character image so we can read pixels - AL Lock image allows us to access image's pixels. Look at each frame of image
For x=(iCellWidth-1) To 0 Step -1 ' work from right to left
For y=0 Until iCellHeight ' check pixels from top to bottom
alpha=ReadPixel(img,x,y) & $ff000000 ' grab alpha ($00=background, $ff=foreground)
If alpha Then Exit ' if foreground then we have our width (in x)
Next
If alpha Then Exit ' if we have our width, no need to continue
Next
UnlockImage imgFont,i ' unlock this character


iWidthTable[i]=x+1 ' store width plus spacing
If x>iMaxWidth Then iMaxWidth=x ' check against widest character
Next
iWidthTable[0]=iMaxWidth*.3 ' calculate width of space

EndMethod


Method DrawBmpFont(text$,x,y)
Local i=0
For i=0 Until text.length
DrawImage imgFont,x,y,Asc(text[i..i+1])-32
x:+iWidthTable[Asc(text[i..i+1])-32]
Next
EndMethod
EndType

Global ArialFont:TFont
ArialFont = New TFont
ArialFont.iFirstASCII = 32
ArialFont.iLastASCII = 126

ArialFont.iCellWidth = 16
ArialFont.iCellHeight = 16

ArialFont.CreateFont("font16p.png")



While Not KeyDown(key_escape)
ArialFont.DrawBmpFont("1. Hello this is a font test",100,100)
ArialFont.DrawBmpFont("2. More text for you",100,200)



Flip
Cls

Wend

*****************************************

BUT...if you change the first 2 lines of the type to:
Field iLastASCII 'Local as it may need to be different for each font object
Field iFirstASCII

ie you remove the values within the type, the following line:

iWidthTable[i]=x+1

..produces the error 'Unhandled Exception: Attempt to index array element beyond array length'

So what is the difference? I understand the error but have no idea why this would happen. What have I missed? Thanks very much for all help.

bradford6
 #6
use {codebox} ... {/codebox}

replace {} with []

Ant
 #7
- sorry, dont understand your last comment replace {} with [] ?

In terms of the code the problem I have found is that iWidthTable doesnt seem to have a size - yet its size seems to be initialised to iWidthTable[iLastASCII-iFirstASCII+1], with iLastASCII and iFirstASCII set when I create the instance...

rich d
 #8
When you want to post long code type "[" followed by "codebox" and a closing "]" on a line. Then type your code, and when you are done type "[" followed by "/" and "codebox" and a final "]".

Check out the forum codes here

Ant
 #9
I got ya.
Thanks