Is it possible to change a Bitmap's image "on the fly"

techdojo

EDIT : YES IT IS! (see Bitmap:setTexture() and Bitmap:setTextureRegion() in 2012.8.2+)

I'm working on a super fast text renderer for which I want to use a single texture atlas containing all the font images that I want to use.

The idea is to have a number of "rows" that can contain text strings of different lengths, over time the contents of these row's will be updated and the text will change - currently whenever a row is updated, I create a new Sprite for the row and then add in a series of new Bitmaps (1 per character), however when there are multiple updates you get nasty spikes in the framerate - which I've tracked down to the amount of garbage being generated for all the above memory allocations.

A much better solution would be to "pre-allocate" a bank of bitmaps for each row (for the max number of possible characters per row contents), set them all to be invisible and then instead of re-creating each Bitmap, just simply change the U,V,Width/Height info for each bitmap effectively making it "point" to a different character in the font texture and then making it visible.

But...

The $64,000 question, is.. is it possible to update the texture region that a bitmap points to without having to create a new one. I'm sure it can be with a Shape using the beginPath, moveTo and lineTo functions but that seems overkill and might even be slower than the Bitmap.new()

I initially considered the TileMap:setTile() function but that would only work with a fixed with font.

Anyone (yeah I'm looking you @Atilim - master of the undocumented functions ) know of a way it can be done on Bitmaps?

As a side note - it'll make bitmap animations an absolute breeze!


PS. If it's NOT possible then prepare to expect a horde of very loud mice *squeaking* this way soon!

techdojo

Bump?

atilim

It's great (and easy to implement) idea and therefore I've already added these functions:

Bitmap:setTexture(Texture or TextureRegion) TextureRegion:setRegion(x, y, width, height) TextureRegion:getRegion() -- returns x, y, width, height

Also I've started to think about Meshes.

techdojo

@Atilm you ARE a star (and I don't mean in the flaming big ball of gas, prone to violent eruptions sense)

Thank you very much ^:)^

Nascode

one *squeak* down

Thank you @atilim

OZApps

It's great (and easy to implement) idea and therefore I've already added these functions:

Bitmap:setTexture(Texture or TextureRegion) TextureRegion:setRegion(x, y, width, height) TextureRegion:getRegion() -- returns x, y, width, height

Also I've started to think about Meshes.

So I guess that can also be used for Animations from spritesheets, right?

So, do you mean we could use something like

local tex = Texture.new("someimage.png") local bmp = Bitmap.new(TextureRegion.new(x,y,wd,ht))

and then somewhere in the code

bmp:getTexture():setTextureRegion(x1,y1,wd1,ht1)

or maybe

bmp:setTextureRegion(x1,y1,wd1,ht1)

techdojo

That's exactly what it could be used for.

If developers embrace this and put all their anims on a single frame it'll make a really big difference to the app running speed - ESPECIALLY if you reuse objects and don't create any new objects in your EnterFrame function

It'll also be a LOT more efficient than using Movieclips for big anims as you won't have to have a single sprite for each frame - just ONE bitmap that you just change the texture on.

atilim

@OZApps exactly. But with one difference, there won't be Bitmap:getTexture() function. You should hold a reference to your TextureRegion somewhere else like:

local texture = Texture.new("someimage.png") local textureRegion = TextureRegion.new(texture, x, y, width, height) local bitmap = Bitmap.new(textureRegion)   -- and then somewhere in the code   textureRegion:setRegion(x1, y1, width1, height1) bitmap:setTexture(textureRegion) -- you should also set texture region so that bitmap gets the parameters

GregBUG

wow... i'm just coding Animator Studio 1.5

OZApps

@Atilim, and this will be in the coming release, right? I was so excited that I wrote some code to create and handle some animation based on that and when I ran it to test it...

Waiting for 2012.8.2

MikeHart

@techdojo: What is the difference in text output between your solution and using BMFont? It uses only one texture map too.

techdojo

The problem with BMFont is that if you want to change the text then a new set of bitmaps will be required (hence memory allocation, garbage collection etc), this solution will allow you to update text every frame without any of that overhead.

Scouser

@techdojo: unless you use my modification to BMFont which allows the font to be a texture region of a larger texture so you could have multiple fonts on the same texture page. I already used this feature in HappyCatz

techdojo

The issue isn't with packing all the images into a single atlas - this is already supported, the issue is being able to change a bitmap's image without having to create a new one and incur all the penalties associated with dynamic memory allocation.

Mells

@atilim Great that you added this

Also I've started to think about Meshes.

From that discussion right?

atilim

From that discussion right?

yes.

btw, previously I was planning to add only Bitmap:setTexture() function that accepts both Texture and TextureRegion objects but now there are two functions Bitmap:setTexture() and Bitmap:setTextureRegion() for setting Texture and TextureRegion objects separately.

techdojo

Woo hoo +1 for the squeakers

Mells

For reference and people that will find this discussion :
Bitmap:setTexture() and Bitmap:setTextureRegion() are now documented [ link ].

Bitmap:setTexture(texture)

Sets the texture.
Parameters:
texture: (TextureBase)

Bitmap:setTextureRegion(textureRegion)

Sets the texture region.
Parameters:
textureRegion: (TextureRegion)

alexzheng

So This modification will make the Button Class a little more efficient?

Button = Core.class(Bitmap)

function Button:updateVisualState(state)
if state then
self:setTexture(self.downState) ---here self.downState is now a Texture
else
self:setTexture(self.upState)
end
end

ar2rsawseen

@alexzheng yes it should, basically as efficient as it can get