I am writing a GUI application that works on Mac and Win and there is one little problem, which i do not know how to solve.
In my application I have a small (250 x 250 px) preview window (let' call it SW) in which placed the image. Image can be much bigger, than SW. Somewhere I have a slider which implements zoom function of image inside SW. My main problem is implement zoom function on this image.
On enter I have:
source image and it's width and height;
view image - it is zoomed copy of source image;
position of zoomed image
size of viewport is 250 x 250 px
It should works like zoom in image processing programs. When we changing our zoom value image becomes smaller or bigger relative to viewport center and position of image inside it. We can move image inside of viewport.
For correct implementation of that problem we need to calculate images size and position inside our view. I'm already wrote some "algo" that implements image size modification.
It is looks like:
float one = (source_original_size - thumbnail_size) / 100;
int bigger_side_size = qRound((100-value) * one) + thumbnail_size;
But I can not imagine how I can calculate position on scene of that zoomed image.
Can anybody help me with ideas?
If it is important I am using Qt framework and QGraphicsView, QGraphicsScene and QGraphicsPixmapItem.
Take a look at the Image Viewer Example, it has some features that you are looking for.
Related
I'm using vtkResliceImageViewer to display image (multi-planar reconstruction). How can I flip\mirror that image vertically and horizontally? Operating with camera is not working as expected, since flip has to take into consideration also camera rotation angle, so it gets very complicated. It would be great if there is a way to change image's texture coordinates. Is this possible?
// Create an image
vtkSmartPointer<vtkImageMandelbrotSource> source =
vtkSmartPointer<vtkImageMandelbrotSource>::New();
source->Update();
// Flip the image
vtkSmartPointer<vtkImageFlip> flipYFilter =
vtkSmartPointer<vtkImageFlip>::New();
flipYFilter->SetFilteredAxis(1); // flip y axis
flipYFilter->SetInputConnection(source->GetOutputPort());
flipYFilter->Update();
// Create the Viewer
vtkSmartPointer<vtkResliceImageViewer> viewer =
vtkSmartPointer<vtkResliceImageViewer>::New();
viewer->SetInputData(flipYFilter->GetOutput())
I have a window with a width of 260 pixels. By using the DrawSurface function I can put an image on the position which is not visible on the screen, for example (500, 10). Now I want to move the screen (by pressing the button) to the point where is the image. Is it possible?
I'm not sure how accurate or up-to-date this article is but it gives a lot of starting code for implementing a makeshift camera using an SDL_Rect variable. In your case, you would modify the x and y variables of the camera object and use the apply_surface() method to show textures relative to the camera's position.
I'm trying to solve this one for hours and I can't figure out where I am going wrong..
On my page there is an image and a "selection frame". This frame can be moved and resized.
I am trying to make the image turn with the center point of the turn being the center of the frame.
I created a small handle at the top for rotation.
Here's the fiddle: http://jsfiddle.net/8PhqX/7/ (give it a minute to load)
The code in the fiddle is very long because I couldn't isolate the specific area relevant to my question. As you play around with it you'll see that the first rotation usually works fine, but then, things go crazy.
Here's the codeline for the rotation:
//selfRotator.handle.angle is the angle(clockwise) at which the rotation handle was rotated
//selfSelector.rotator.ox/oy is the position of the middle of the selection frame
//selfDefaults.imageArea.y is the y position of the section with the image (because of the red stripe in the top)
//selfImageArea.page.startX/Y is starting position of the image storing its position when the drag begins
//rotating by angle, at center point of selection
selfImageArea.page.transform(
['r', -selfRotator.handle.angle, selfSelector.rotator.ox - selfImageArea.page.startX, selfSelector.rotator.oy - (selfImageArea.page.startY - selfDefaults.imageArea.y)]
)
//tracking the image's start position and compensating
selfImageArea.page.attr({
transform: "...T" + (selfImageArea.page.startX) + "," + (selfImageArea.page.startY - selfDefaults.imageArea.y)
});
It looks like it gets messed up because of the getBBox values that don't follow the picture outlines.
I've added gridlines to illustrate the problem
also, iv'e came across this code(https://groups.google.com/forum/#!topic/raphaeljs/b8YG8DfI__g) for "getBBoxRotated()" function that should solve my issue but I can't seem to implement it.
I have 2 points A and B. The distance is 100 and my sprite image is 50. My question is can I resize the sprite from the center of the image in order to keep the quality and if its possible how can I do that? I tried with this code, but it just scale the image width and look awful.
-(void)resizeSprite:(CCSprite*)sprite toWidth:(float)width toHeight:(float)height {
sprite.scaleX = width / sprite.contentSize.width;
sprite.scaleY = height / sprite.contentSize.height;
Not sure if this is what you're after - but if you just want to scale the sprite to twice the size without artefacts you can use linear filtering on the sprite texture
[sprite.texture setAliasTexParameters];
Then just scale it to whatever you like
[sprite setScale: 2.f];
Thanks for reading.
I'm working on a setup in Cocos2D 1.x where I have a huge CCLayerPanZoom in a scene with free panning and zooming.
Every frame, I have to additionally draw a CCRenderTexture on top to create "darkness" (I'm cutting out the light). That works well.
Now I've added single sprites to the surface, and they are managed by Box2D. That works as well. I can translate to the RenderTexture where the light sources ought to be, and they render fine.
And then I wanted to add a HUD layer on top, by adding a CCLayer to the scene. That layer needs to contain several sprites stacked on top of each other, as user interface elements.
Only, all of these elements fail to draw where I need them to be: Exactly in the center of screen. The Sprites added onto the HUD layer are all off, and I have iterated through pretty much every variation "convertToWorldSpace", "convertToNodeSpace", etc.
It is as if the constant scaling by the CCPanZoomLayer in the background throws off anchor points in the layer above each frame, and resetting them doesn't help. They all seem to default into one of the corners of the node bounding box they are attached to, as if their transform is blocked or set to zero when it comes to the drawing.
Has anyone run into this problem? Is this a known issue when using CCLayerPanZoom and drawing a custom CCRenderTexture on top each frame?
Ha! I found the culprit! There's a bug in Cocos2D' way of using Zwoptex data. (I'm using Cocos2D v 1.0.1).
It seems that when loading in Zwoptex v3 data, sprite frames' trim offset data is ignored when the actual sprite frame anchor point is computed. The effect is that no anchor point on a sprite with trim offset in its definition (eg in the plist) has its anchor point correctly set. Really strange... I wonder whether this has occurred to anybody else? It's a glaring issue.
Here's how to reproduce:
Create any data for a sprite frame in zwoptex v3 format (the one that uses the trim data). Make sure you actually have a trimmed sprite, i.e. offset must be larger than zero, and image size must be larger than source.
Load in sprite, and try to position it at center of screen. You'll see it's off. Here's how to compute your anchor point correctly:
CCSprite *floor = [CCSprite spriteWithSpriteFrameName:#"Menu_OmeFloor.png"]; //create a sprite
CCSpriteFrame *frame=[[CCSpriteFrameCache sharedSpriteFrameCache] spriteFrameByName:#"Menu_OmeFloor.png"]; //get its frame to access frame data
[floor setTextureRectInPixels:frame.rect rotated:frame.rotated untrimmedSize:frame.originalSizeInPixels]; //re-set its texture rect
//Ensure that the coordinates are right: Texture frame offset is not counted in when determining normal anchor point:
xa = 0.5 + (frame.offsetInPixels.x / frame.originalSizeInPixels.width);
ya = 0.5 + (frame.offsetInPixels.y / frame.originalSizeInPixels.height);
[floor setAnchorPoint:ccp(xa,ya)];
floor.position=(where you need it);
Replace the 0.5 in the xa/ya formula with your required anchor point values.