What's wrong with my blitting code?

MagerValp · 22 April 2013, 08:39

Hi all,
instead of Text()ing straight into my window's rastport I'd like to write it to an offscreen bitmap and then blit that. For some reason all I get is garbled graphics. Could someone please tell me what I'm doing wrong here?

Test program with source:

https://www.dropbox.com/s/l3kc3992e9u6g5e/testblit.lha

Relevant snippet:

Code:

    NEW bm
    InitBitMap(bm, 4, 256, 8)
    FOR i := 0 TO 3
        bm.planes[i] := NIL
    ENDFOR
    FOR i := 0 TO 3
        bm.planes[i] := AllocRaster(256, 8)
        IF bm.planes[i] = NIL
            Raise("MEM")
        ENDIF
    ENDFOR
    
    NEW rp
    InitRastPort(rp) -> This was missing, thanks to thomas for pointing it out
    rp.bitmap := bm
    SetRast(rp, 8)
    
    SetABPenDrMd(rp, 15, 14, RP_JAM2)
    SetFont(rp, font)
    Move(rp, 0, rp.font.baseline)
    Text(rp, ' Text() into off screen bitmap ', 31)
    
    BltBitMapRastPort(bm, 0, 0,
                      w.rport, 32, 48,
                      256, 8,
                      $0c0)

thomas · 22 April 2013, 09:29

InitRastPort() is missing.

MagerValp · 22 April 2013, 10:19

Confirmed, thank you!

thomas · 22 April 2013, 10:53

So now it works as intended?

One more hint: you are using SetABPenDrMd which only exists in 2.0+. Knowing this you could also use AllocBitMap which would be much easier than to allocate and initialize your own bitmap structure.

MagerValp · 22 April 2013, 10:58

Yep, happily blits text now. Unfortunately AllocBitMap() is V39 and I need to support V37.

thomas · 22 April 2013, 11:31

Ok, it's not 2.0+ but 3.0+, but my hint is still valid. Both SetABPenDrMd and AllocBitMap only exist in 3.0+.

MagerValp · 22 April 2013, 15:00

Ah, you're right, this is just my test code though, the real code doesn't call SetABPenDrMd at all:

https://github.com/MagerValp/ArcadeG...GS2Menu.e#L249

22 April 2013, 08:39	#1
MagerValp Registered User Join Date: Aug 2008 Location: Göteborg / Sweden Posts: 237	What's wrong with my blitting code? Hi all, instead of Text()ing straight into my window's rastport I'd like to write it to an offscreen bitmap and then blit that. For some reason all I get is garbled graphics. Could someone please tell me what I'm doing wrong here? Test program with source: https://www.dropbox.com/s/l3kc3992e9u6g5e/testblit.lha Relevant snippet: Code: NEW bm InitBitMap(bm, 4, 256, 8) FOR i := 0 TO 3 bm.planes[i] := NIL ENDFOR FOR i := 0 TO 3 bm.planes[i] := AllocRaster(256, 8) IF bm.planes[i] = NIL Raise("MEM") ENDIF ENDFOR NEW rp InitRastPort(rp) -> This was missing, thanks to thomas for pointing it out rp.bitmap := bm SetRast(rp, 8) SetABPenDrMd(rp, 15, 14, RP_JAM2) SetFont(rp, font) Move(rp, 0, rp.font.baseline) Text(rp, ' Text() into off screen bitmap ', 31) BltBitMapRastPort(bm, 0, 0, w.rport, 32, 48, 256, 8, $0c0) Last edited by MagerValp; 22 April 2013 at 10:20. Reason: Updated with answer from thomas

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
I need quick transparent blitting	meynaf	Coders. General	15	13 November 2020 16:08
Blitting question	sandruzzo	Coders. General	30	06 April 2011 11:29
Bitmaps in FASTRAM and blitting - C++	NovaCoder	Coders. General	22	01 December 2010 23:40
Blitting with size 1x255	JackAsser	Coders. Tutorials	10	16 February 2010 20:49
difference in blitting uae vs. hw	yoki	Coders. General	5	15 July 2009 15:21

22 April 2013, 09:29	#2
thomas Registered User Join Date: Jan 2002 Location: Germany Posts: 6,985	InitRastPort() is missing.

22 April 2013, 10:19	#3
MagerValp Registered User Join Date: Aug 2008 Location: Göteborg / Sweden Posts: 237	Confirmed, thank you!

22 April 2013, 10:53	#4
thomas Registered User Join Date: Jan 2002 Location: Germany Posts: 6,985	So now it works as intended? One more hint: you are using SetABPenDrMd which only exists in 2.0+. Knowing this you could also use AllocBitMap which would be much easier than to allocate and initialize your own bitmap structure.

22 April 2013, 10:58	#5
MagerValp Registered User Join Date: Aug 2008 Location: Göteborg / Sweden Posts: 237	Yep, happily blits text now. Unfortunately AllocBitMap() is V39 and I need to support V37.

22 April 2013, 11:31	#6
thomas Registered User Join Date: Jan 2002 Location: Germany Posts: 6,985	Ok, it's not 2.0+ but 3.0+, but my hint is still valid. Both SetABPenDrMd and AllocBitMap only exist in 3.0+.

22 April 2013, 15:00	#7
MagerValp Registered User Join Date: Aug 2008 Location: Göteborg / Sweden Posts: 237	Ah, you're right, this is just my test code though, the real code doesn't call SetABPenDrMd at all: https://github.com/MagerValp/ArcadeG...GS2Menu.e#L249

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)