A few weeks ago I spent a weekend getting this up and running on windows. Now I need to get it working on mac and linux and check it in. I'd appreciate as much input on the design as possible. I'll post my patch asap.
Random platform buddies and rendering fanboys. /be
I just tried out your build and the testcases. This is AWESOME! (Especially the seizure testcase)
Just adding myself to CC, gonna really look later. You posted that this is a RGB image? Could this be a RGBA image, too? That would be really nifty. (And it's gonna be slow, too;-)) Axel
hewitt: why <xul:canvas/> instead of display:-moz-xul-canvas ?
is there a reason you have the NPL header copyright 1998 at the top of all the new files?
uh. mozilla is doing odd things. ignore my previous comment
bah. stupid session history.
test cases work great. cant wait to see this on mac and linux.
Joe, any updates on this? Would it be possible to make this an .xpi ?
Can someone post the demos that were linked from this bug? That link no longer works. Thanks.
Are there any plans for continuing work on this? Target Milestone was set to 1.1Alpha, and we're at 1.4RC1 now... I think a xul canvas element would greatly enhance Mozilla-the-platform's value as a base for applications. For example, the people at http://games.mozdev.org would certainly like it, and we at optimoz mouse gestures would be glad if we no longer had to paint mouse trails by inserting DIVs via DOM...
I ported the code to work in the latest 1.5 builds, but nothing displays on the screen. Maybe I am doing something wrong (but I can't imagine what). Joe, do you still have the examples?
I am just going to take this bug. I think my problem is something with the drawing code, they changed a few things in the last 2 years :-) Since this would (probably) never be allowed to become a real XUL element, I will try to just make this a scriptable component and an XBL that can be installed through an XPI. When I get this working I'll just throw it on mozdev. I want to use this thing for a game too :-P
Created attachment 129486 [details] canvas demos Here are the old canvas demos, I found them on a backup CD. Hope they are of some assistance.
Thanks Joe, they have/will help. I've got some drawing happening on the screen now, but the colors don't seem to be working. Anyways, back to work...
Eric, speaking of colors: it would be nice if the canvas allowed basic transparency, so one can stack it upon other elements that shine through "unpainted" areas of the canvas (no immediate need for sophisticated full alpha channel support - I guess that will be too slow anyway). If you need help, I'll do what I can (mainly qa/testcases and JS/XUL stuff I guess, did not hack mozilla cpp yet).
Just to post an update... I had my hard drive die on me at the wrong time, losing the code that I ported up to work in 1.5 code :-( However, much of that code that I changed has little to do with making canvas it's own component. No progress was really lost, but this has all set me back time-wise. I am setting a project up at canvas.mozdev.org soon. I'll probably just close out this bug soon and all code and updates will be posted there.
Eric, does that mean it won't ever be included in the trunk? I think it would be best if the canvas would be in the official builds...
That will probably never happen. It's not a XUL element, and is a non-standard element. Maybe if it gets a good response (when it's done), I'll suggest it to whoever will listen to be added to the builds.
Neal Deakin <email@example.com> has created a resurrected version of this patch at http://www.xulplanet.com/ndeakin/tests/canvas/canvas-patch-main.txt I will be taking on some crash and stability cleanup of that patch, and then attempting the proper reviews to get it landed. Some particular changes have been suggested by Roc: Remove the lock/unlockPixels methods, and change the setPixel methods to setPixelRow to set an entire row at a time. He wants to use an octet-triple array, while I'm still thinking a nscolor (0xRRGGBBAA) array would be easier to construct, especially if you're drawing solid-color areas. In addition, I might be able to get a JS-specialty method that draws pixels from a two-dimensional array (it's not representable in IDL, but using ClassInfo and a scriptablehelper it should be possible). Remove the set/getColorString param, which is just redundant. Remove the cached option entirely. Roc is hoping to get rid of the offscreen-drawing-surface impl altogether, and unless someone presents an killer use-case for a cached rendering context we'll just use the render-as-needed approach. I'm adding text-measurement APIs to the scriptable rendering context, and making sure that all coordinates are nscoord (signed long) IDL typed. Do I need to add pixel-to-twip conversion factors
Benjamin, can you say more about what that JS specialty method would look like? Maybe we *should* extend IDL a bit (it's about time! ;-). /be
Having a cached surface is useful for drawing image-like things, or doing animation where the changes from one frame to the next are minimal. Having to call to JS to redraw the contents every repaint can be slow. The cached version doesn't need to call to JS. Instead of a buffer, the actual image classes could be used instead, but those are awkward to draw to from scripts. Perhaps images could be made to implement nsIScriptableRenderingContext one day.
> Benjamin, can you say more about what that JS specialty method would look like? > Maybe we *should* extend IDL a bit (it's about time! ;-). If we're going for the "idl-extension" route, support for n-dimensional arrays of fixed size in all three dimensions, such: void setPixels(in nscoord x, in nscoord y, in unsigned long width, in unsigned long height, [array(2), size_is(height, width)] in gfx_color pixels); if we're talking about the scriptable-helper method, the IDL definition would be empty: void setPixels(), and the scriptable rendering context would implement nsIXPCScriptable::Call and manually handle the JS call context which would have a two-dimension array object passed in. Note that this discussion is somewhat theoretical; I'm not going to do it in a first-revision patch in any case ;) My xpconnect/JS FU is not that good.
I guess I can live with the buffer. The user specifies at the start whether to use retained mode or not? How do you compute the invalid rect/region in retained mode? I personally don't feel this is the time or the way to extend IDL... Regarding choice of units, first read http://ocallahan.org/mozilla/units.html to understand some issues, if you haven't already I think the way to go here is to specify that all units are CSS pixels. [In a future revision of this API we can add tranforms, then users will be able to apply a scaling-down transform and work in a higher resolution space to get better visual results for high-res devices.] So you may want to have a function to return the number of CSS pixels per inch.
Since scaling may be involved, we probably want a single function that can paint an entire rectangle of pixels, not just one row like I suggested before. Maybe a good way to go would be to just provide an API that can take an RGB array and turn it into an image, and then the user can call drawImage etc. An additional API to use RGBA could be provided too. Another thing to think about is transparency. I suggest not providing alpha-aware APIs at this time since we don't have good support yet (except for in images). However, you want the canvas to be able to be transparent so you can see what's behind it. This is trivial in immediate mode (unbuffered). In retained mode you really want the buffer to be RGBA (along with a function to set pixels to transparent) but we don't support that well yet. An interim solution would be to specify a background color when you enter retained mode, set the buffer to that color, and for now don't support transparent pixels in retained mode.
Come to think of it, you don't need an IDL extension to do n-dimensional arrays; the IDL could be prototyped thus: void drawPixels(in nscoord x, in nscoord y, in unsigned long columnCount, in unsignedLong pixelCount, [array, size_is(numPixels)] in nscolor); So the number of rows would be pixelCount/columnCount. roc: why is (octet, octet, octet) better than a single 32-bit value RRGGBBAA (we typedef gfx_color == nscolor to "unsigned long" in IDL to make it scriptable)? IMO the single value would be a lot more efficient from an xpconnect perspective (and allow aligned 32-bit reads from the c++ side), and would allow the API to do transparency whenever it becomes available without changing the interface.
Robert O'Callahan wrote: > Another thing to think about is transparency. I suggest not providing > alpha-aware APIs at this time since we don't have good support yet (except for > in images). Maybe we even need support for a "capabilities" API that XUL applications can query whether alpha channel is supported or not. Remember that Mozilla's PostScript print module doesn't support an alpha channel nor offscreen surfaces nor copying of surface data so we may need such an API (since I doubt that the PostScript module will ever be redesigned to support this).
Agree with bsmedberg on 32-bit color 4-tuples over octet array madness. Roc, what are we missing? Always glad to avoid IDL extensions -- I was just asking. But since we're being touted as a platform, lack of structs does hurt us compared to MS COM. Who cares, given .NET? XPCOM cares, it has a long life ahead of it. Roland, I've seen too many capability-menu APIs (PHIGS, anyone) go south because apps have to write combinatorially explosive code querying all the capabilities and implementing fallbacks for missing caps. This sucks, and leads to one set of "required default" caps emerging -- so why waste time and space on the menu? /be
firstname.lastname@example.org wrote: > Roland, I've seen too many capability-menu APIs (PHIGS, anyone) go south > because apps have to write combinatorially explosive code querying all the > capabilities and implementing fallbacks for missing caps. This sucks, and > leads to one set of "required default" caps emerging -- so why waste time and > space on the menu? ... because we have a certain platform with a certain renderer which doesn't support that feature... ;-/ I am only asking for a way to query the capabilities. Applications should be free to ignore it but if an application has the ability to use an alternative path in that case we would need a query mechanism that the application can distinguish between both cases.
On the capability menu API point -- while I agree w/ Brendan that it's traditionally been a pain, I have also seen recent stuff which seems to indicate that there is a great deal of overlap in 'base functionality'. Things like transparency and rotated text are now almost the only things that you'll find in some backends and not others that I would consider part of the scope of a XUL painting control (color blending models etc. I consider out of scope). (See e.g. http://www.scipy.org/site_content/chaco/intro for a description of a fairly rich graphics package based on this model). --david ascher
David Ascher wrote: > On the capability menu API point -- while I agree w/ Brendan that it's > traditionally been a pain, How do you suggest should the issue be solved then ? I doubt that anyone will step-up and add alpha channel support to the PostScript print module. As long we have such problems we should provide a way to detect the issue and work around it.
Neil, do you still work on the canvas stuff? If so, what's the status?
Benjamin, any news on the implementation? It would be very sad if this disappeared again just after being "resurrected" with a working patch...
(In reply to comment #37) > It would be very sad if this disappeared again just after being "resurrected" > with a working patch... Since the last (public) patch dates back to Dec 3, 2003, this is probably the case. Prog.
13 years ago
Just a datapoint: I tried the one in Safari 2.0 (172) included in recent Tiger prerelease builds (8A323), and it does seem to work fine with the basic things I tried (several hundred animated rectangles of various colors).
There's an entirely new canvas implementation coming, based on Cairo, with much more functionality. And it's Apple compatible.
(In reply to comment #40) > There's an entirely new canvas implementation coming, based on Cairo, with much > more functionality. And it's Apple compatible. Is 'new canvas implementation' bug 288714 ?
Yes and as that can be used in XUL as well using the XHTML namespace I think this bug can be resolved, not?
Not yet; the other canvas contains just a simple HTML drawing surface element, as defined by WHATWG/Apple. Neil had some great ideas about how a canvas would fit well into XUL, and those should still be implemented for <xul:canvas>. It can share the back-end rendering contexts with the HTML <canvas>, while adding child element positioning and other similar features that are of more interest in XUL.
I don't understand why this is not a duplicate of bug 288714. Could someone explain? (I would think that it would be confusing if xul:canvas is wildly different from html:canvas.)
Mainly history. *** This bug has been marked as a duplicate of 288714 ***
how is this bug resolved? there isn't a xul:canvas tag.