Any suggestions on how to replicate the HatchStyle from GDI in Direct2D ?
https://msdn.microsoft.com/en-us/library/windows/desktop/dd144966%28v=vs.85%29.aspx
What to consider :
1) The color of the lines must be the same as the color of the Brush, like in GDI.
2) Must be performant
So far, here are my potential solutions :
1) Use a ID2D1BitmapBrush on which I draw the lines with the specified color.That means I need to recreate the brush every time the colors changes or when the HatchStyle changes. Draw the BitmapBrush on the specified area and take advantage of the BitmapBrush ExtendMode WRAP to repeat the pattern in X and Y.
2) Draw all the lines one by one over the area with the specified color.
Here's another choice: create two masks, one for the primary color and the other for the secondary color (which should just be the inverse of the first mask). Then call FillOpacityMask twice. The first call will use the first mask + a solid color brush for the primary color, and the second call is second mask + solid color brush for the secondary color.
Related
I have a general question (I know I should present specific code with a problem, but in my case the problem is of a more general nature).
In Processing, let's say I make an ellipse:
ellipse(30, 30, 10, 10);
Now, is there a way to get the pixels where this ellipse is on the canvas? The reason would be to have a way of creating user interaction with the mouse (for instance). So when someone clicks the mouse over the ellipse, something happens.
I thought of turning everything into objects and use a constructor to somehow store the position of the shape, but this is easier said than done, particularly for more complex shapes. And that is what I am interested in. It's one thing to calculate the position of an ellipse, but what about more complex shapes? Are there any libraries?
Check out the geomerative library. It has a way to check whether the mouse is inside any SVG shape. I can't remember off the top of my head but it works something like you make a shape:
myShape = RG.loadShape("shape.svg");
and a point:
RPoint p = new RPoint(mouseX, mouseY);
and the boolean function contains() will tell you if the point is inside the shape:
myShape.contains(p);
It's better to use a mathematical formula than pixel-by-pixel checking of the mouse position (it's much faster, and involves less code).
For a perfect circle, you can calculate the Euclidean distance using Pythagoras' theorem. Assume your circle is centred at position (circleX,circleY), and has a radius (not diameter) of circleR. You can check if the mouse is over the circle like this:
if(sq(mouseX-circleX)+sq(mouseY-circleY) <= sq(circleR)) {
// mouse is over circle
} else {
// mouse is not over circle
}
This approach basically imagines a right-angled triangle, where the hypotenuse (the longest side) runs from the centre of the circle to the mouse position. It uses Pythagoras' theorem to calculate the length of that hypotenuse, and if it's less than the circle's radius then the mouse is inside the circle. (It includes a slight optimisation though -- it's comparing squares to avoid doing a square root, as that can be comparatively slow.)
An alternative to my original mathematical answer also occurred to me. If you can afford the memory and processing power of drawing all your UI elements twice then you can get good results by using a secondary buffer.
The principle involves having an off-screen graphics buffer (e.g. using PGraphics). It must be exactly the same size as the main display, and have anti-aliasing disabled. Draw all your interactive UI elements (buttons etc.) to this buffer. However, instead of drawing them the normal way, give each one a unique colour which it uses for fill and stroke (don't add any text or images... just solid colours). For example, one button might be entirely red, and another entirely green. Any other RGB value works, as long as each item has a unique colour. Make sure the background has a unique colour too.
The user never sees that buffer, so don't draw it to the screen (unless you're debugging or something). When you want to detect what item the mouse is over, just lookup the mouse position on that off-screen buffer. Get the pixel colour at that location, and match it to the UI element.
After you've done all that, just go ahead and draw everything to the main display as normal.
It's worth noting that you can cut-down the processing time of this approach a lot if your UI elements never (or rarely) move. You only need to redraw the secondary buffer when something appears/disappears, animates, or changes size/position.
Sorry for the bad title I don't really know how could I write it better. I want to create a colorpicker that's not very typical. There is the version where you can select the three vectors of HSB. It would be close to it but not at all. The main problem is why I don't use the usual colorpickers is that I have a very specific space to do it. I have 35 free objects that could be colored (these are filled circles with a black border) and not more. But I can place each object wherever I want. So how I imagine there would be a circle of 12-18 objects that are constats they would represent the HUE than when I select one the rest of the objects would be in the HUE circle and they would form a square. And why I call it tree: because you could select a color from the main circle than you get colors from that branch than you click on one of the colors in the got colors than you get colors from that color (but the clicked color is always part of the "zoomed" colors the best how you can imagine this like there is the HSB color space and in the first two clicks you select the HUE than you just zoom in the HSB color space than there is the two dimensional 101*101 S and B square and we zoom on the color. I really hope that you can understand me if not ask anything. And thank you for reading this long text.
Something like this:
The first, must know what is equation of HSB Color. The Algorithm to find this is in this with name HSV.
If you found, You can fill each color with choosen formula with hue you choosen and full saturation.
Add listener of click for that circle.
In listener, update the cicle inside with your choosen saturation and brighness. For example first row is sqaturation and brightness is column. Then in row 1 is no saturation, row 2 is half saturated(50) and row 3 is full saturated ones. The column 1 is the brightmost one(100) the 2 is half(50) and 3 is no brightness (0), for example.
Aclually it is not a tree, but a alternative approach for standard approach because it's more like that than tree.
I got a png image like this:
The blue color is represent transparent. And all the circle is a pixel group. So, I would like to find the biggest one, and remove all the small pixel, which is not group with the biggest one. In this example, the biggest one is red colour circle, and I will retain it. But the green and yellow are to small, so I will remove them. After that, I will have something like this:
Any ideas? Thanks.
If you consider only the size of objects, use the following algorithm: labellize the connex components of the mask image of the objects (all object pixels are white, transparent ones are black). Then compute the areas of the connex components, and filter them. At this step, you have a label map and a list of authorized labels. You can read the label map and overwrite the mask image with setting every pixel to white if it has an authorized label.
OpenCV does not seem to have a labelling function, but cvFloodFill can do the same thing with several calls: for each unlabeled white pixel, call FloodFill with this pixel as marker. Then you can store the result of this step in an array (of the size of the image) by assigning each newly assigned pixel with its label. Repeat this as long as you have unlabellized pixels.
Else you can recode the connex component function for binary images, this algorithm is well known and easy to implement (maybe start with Matlab's bwlabel).
The handiest way to filter objects if you have an a priori knowledge of their size is to use morphological operators. In your case, with opencv, once you've loaded your image (OpenCV supports PNG), you have to do an "openning", that is an erosion followed by a dilation.
The small objects (smaller than the size of the structuring element you chose) will disappear with erosion, while the bigger will remain and be restored with the dilation.
(reference here, cv::morphologyEx).
The shape of the big object might be altered. If you're only doing detection, it is harmless, but if you want your object to avoid transformation you'll need to apply a "top hat" transform.
I have more then 1 week reading about selective color change of an image. It meand selcting a color from a color picker and then select a part of image in which I want to change the color and apply the changing of color form original color to color of color picker.
E.g. if I select a blue color in color picker and I also select a red part in the image I should be able to change red color to blue color in all the image.
Another example. If I have an image with red apples and oranges and if I select an apple on the image and a blue color in the color picket, then all apples should be changing the color from red to blue.
I have some ideas but of course I need something more concrete on how to do this
Thank you for reading
As a starting point, consider clustering the colors of your image. If you don't know how many clusters you want, then you will need methods to determine whether to merge or not two given clusters. For the moment, let us suppose that we know that number. For example, given the following image at left, I mapped its colors to 3 clusters, which have the mean colors as shown in the middle, and representing each cluster by its mean color gives the figure at right.
With the output at right, now what you need is a method to replace colors. Suppose the user clicks (a single point) somewhere in your image, then you know the positions in the original image that you will need to modify. For the next image, the user (me) clicked on a point that is contained by the "orange" cluster. Then he clicked on some blue hue. From that, you make a mask representing the points in the "orange" cluster and play with that. I considered a simple gaussian filter followed by a flat dilation 3x5. Then you replace the hues in the original image according to the produced mask (after the low pass filtering, the values on it are also considered as a alpha value for compositing the images).
Not perfect at all, but you could have a better clustering than me and also a much-less-primitive color replacement method. I intentionally skipped the details about clustering method, color space, and others, because I used only basic k-means on RGB without any pre-processing of the input. So you can consider the results above as a baseline for anything else you can do.
Given the image, a selected color, and a target new color - you can't do much that isn't ugly. You also need a range, some amount of variation in color, so you can say one pixel's color is "close enough" while another is clearly "different".
First step of processing: You create a mask image, which is grayscale and varying from 0.0 to 1.0 (or from zero to some maximum value we'll treat as 1.0), and the same size as the input image. For each input pixel, test if its color is sufficiently near the selected color. If it's "the same" or "close enough" put 1.0 in the mask. If it's different, put 0.0. If is sorta borderline, put an in-between value. Exactly how to do this depends on the details of the image.
This might work best in LAB space, and testing for sameness according to the angle of the A,B coordinates relative to their origin.
Once you have the mask, put it aside. Now color-transform the whole image. This might be best done in HSV space. Don't touch the V channel. Add a constant to S, modulo 360deg (or mod 256, if S is stored as bytes) and multiply S by a constant chosen so that the coordinates in HSV corresponding to the selected color is moved to the HSV coordinates for the target color. Convert the transformed S and H, with the unchanged L, back to RGB.
Finally, use the mask to blend the original image with the color-transformed one. Apply this to each channel - red, green, blue:
output = (1-mask)*original + mask*transformed
If you're doing it all in byte arrays, 0 is 0.0 and 255 is 1.0, and be careful of overflow and signed/unsigned problems.
I'm using GDI+ in my application, and I need to use a rotated LinearGradientBrush to paint several rects in the exact same way. However, although I'm calling the same code to fill each rect, the results aren't what I expect. Here's the code to create the gradient fill, where rcDraw is the rect containing the area to paint for each rect. These coordinates are in the parent window's coordinates, so they are not identical for the 2 rects.
g_hbrLinear = new LinearGradientBrush( Rect( 0, rcDraw.top, 0, rcDraw.bottom - rcDraw.top ),
clrStart, clrEnd, (REAL) 80, FALSE );
What I see on screen looks like this (http://www.nnanime.com/bugs/LinGradBrush-rotate10.png). You can see that it's as if the fill from the first rect continues into the second one. What I really want is to have the 2 rects look identical. I think I can do that if I paint each rect separately using its own client coordinates, but for the purposes of my app, I need to use the parent window's coordinates.
I guess what I'm asking is, how does GDI+ calculate the "origin" of a fill? Is it always based on 0,0 in the coordinate system you use? Is there a way to shift it? I tried TranslateTransform, but it doesn't seem to shift the fill in a way that I find predictable or understandable.
The rect passed to the linear gradient brush determines the where the left and right colors will sit, and the gradient will be painted within this rectangle.
So, I think you need to create a brush for each rectangle you are painting, where the rectangle you are painting is also passed to the constructor for the linear gradient brush.
My experience with the "transform" of linear gradient brushes matches yours; I haven't been able to understand what it's supposed to do.
You can think of a brush in GDI+ as a function mapping world co-ordinates to a color. What the brush looks like at a given point does not change based on the shape being filled.
It does change with the transform of the Graphics object you're drawing on. So, if you don't want to change the brush, you could temporarily change the transform of the Graphics object so that the rectangle you're drawing has a specific, known size and position in world coordinates. The BeginContainer and EndContainer methods should make this easy.
(There is also the RenderingOrigin property but it only affects hatch brushes, which oddly are unaffected by world transforms.)