CALayer scale transform
Is it expected behavior that when applying a CATransform3DMakeScale() transform to a CALayer the layer's current bitmap information is what gets scaled (using some type of filter) rather than asking the layer to actually redraw itself into the, presumably, freshly transformed context? Currently applying a scale transform appears to result in unacceptable pixelation. Here is an example: _textLayer = [[CATextLayer alloc] init]; [_textLayer setFrame:CGRectMake( 300.0, 300.0, 1000.0, 36.0 )]; [_textLayer setString:@Hello world]; [_textLayer setTransform:CATransform3DMakeScale( 1.5, 1.5, 1.0 )]; This will scale the text up to 1.5x its size, but the result is essentially useless. It becomes even more pronounced if I set the minification/magnification filters to nil: [_textLayer setMinificationFilter:nil]; [_textLayer setMagnificationFilter:nil]; I can't seem to find anything in the documentation on this behavior. The relevant sections discuss it as transforming a layer's geometry. Maybe I'm not understanding something fundamental, but I would have figured that a geometry transform wouldn't simply stretch the existing device pixel based bitmap content using minification/magnification filters to fit into the newly scaled unit size (at least, from my understanding, this certainly isn't how a transform applied to the drawing context would cause regular Cocoa drawing to behave). I can understand this being done if the layer content is a bitmap image to begin with, but I certainly wouldn't expect this to be the case for text. Can anyone shed any light on this? /brian smime.p7s Description: S/MIME cryptographic signature ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [EMAIL PROTECTED]
Re: CALayer scale transform
On Jun 11, 2008, at 8:56 AM, Brian Christensen wrote: Is it expected behavior that when applying a CATransform3DMakeScale() transform to a CALayer the layer's current bitmap information is what gets scaled (using some type of filter) rather than asking the layer to actually redraw itself into the, presumably, freshly transformed context? Currently applying a scale transform appears to result in unacceptable pixelation. This is expected behavior. I can't seem to find anything in the documentation on this behavior. The relevant sections discuss it as transforming a layer's geometry. Maybe I'm not understanding something fundamental, but I would have figured that a geometry transform wouldn't simply stretch the existing device pixel based bitmap content using minification/ magnification filters to fit into the newly scaled unit size (at least, from my understanding, this certainly isn't how a transform applied to the drawing context would cause regular Cocoa drawing to behave). I can understand this being done if the layer content is a bitmap image to begin with, but I certainly wouldn't expect this to be the case for text. Effectively a CALayer represents a texture with the layer's contents on the video card. As the docs say, transforms only affect geometry. The texture does not include geometry, thus the current content is scaled rather than being re-rendered. At even moderate zoom factors scaling the content could cause issues with maximum texture sizes on the video card your running on. -- David Duncan Apple DTS Animation and Printing [EMAIL PROTECTED] ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [EMAIL PROTECTED]
Re: CALayer scale transform
On Jun 11, 2008, at 12:37 , David Duncan wrote: Effectively a CALayer represents a texture with the layer's contents on the video card. As the docs say, transforms only affect geometry. The texture does not include geometry, thus the current content is scaled rather than being re-rendered. At even moderate zoom factors scaling the content could cause issues with maximum texture sizes on the video card your running on. I see. Thanks for the explanation. My solution will then be to simply maintain my own scaleFactor and apply that to my drawing calculations in place of a transformation (or in the case of a text layer, simply fontSize * scaleFactor). /brian smime.p7s Description: S/MIME cryptographic signature ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [EMAIL PROTECTED]
Re: CALayer scale transform
On 11 Jun '08, at 9:37 AM, David Duncan wrote: Effectively a CALayer represents a texture with the layer's contents on the video card. As the docs say, transforms only affect geometry. The texture does not include geometry, thus the current content is scaled rather than being re-rendered. At even moderate zoom factors scaling the content could cause issues with maximum texture sizes on the video card your running on. Are all layers treated as bitmap textures, even solid ones? For instance, if I create a 1024x1024 layer as a background and just set its background color to blue, does that allocate a megapixel's worth of VRAM? What about if I add a border or round corners? I've wondered about this with the Grid class in GeekGameBoard, which is used to represent things like chess or Go boards. Is it better to use one big layer with a custom drawing proc that draws the squares, or 64 (or 324) smaller layers? (I've seen some bad CA performance problems on, um, systems with less- capable graphics hardware than the average Mac, which make me wonder if I need to rethink some of the design.) —Jens smime.p7s Description: S/MIME cryptographic signature ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [EMAIL PROTECTED]
Re: CALayer scale transform
On Jun 11, 2008, at 12:39 PM, Jens Alfke wrote: Are all layers treated as bitmap textures, even solid ones? For instance, if I create a 1024x1024 layer as a background and just set its background color to blue, does that allocate a megapixel's worth of VRAM? What about if I add a border or round corners? Layers only use textures / VRAM for the images or drawn content you provide. None of the other features (background color, border color) use any texture memory. (Colors that are patterns allocate a texture for the single image cell in the pattern, but not for the layer size.) I've wondered about this with the Grid class in GeekGameBoard, which is used to represent things like chess or Go boards. Is it better to use one big layer with a custom drawing proc that draws the squares, or 64 (or 324) smaller layers? For small checks a single layer with a pattern-based background color would be best. For large checks multiple layers may be more efficient. The best way to investigate this kind of thing is via the OpenGL Driver Monitor application, you can use it to display the amount of free VRAM over time, John ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [EMAIL PROTECTED]
