I'm currently making a 2D game engine, and I'm working in the messages for the characters, for this I'm using the fillText method of 2DContext however I have no idea how to stroke a text, I have already tried this way:
context.lineWidth = 1;
context.strokeStyle = '#000';
context.fillText(line, x, y);
context.stroke();
But it doesnt work, I already modified the text color and style like so:
context.font = '18pt Arial';
context.fillStyle = "black";
But no clue about the stroke.
When working with the Canvas, the cascade operator .. can help make the code more readable:
context..lineWidth = 3
..strokeStyle = "black"
..strokeText(line, x, y)
..fillStyle = "white"
..fillText(line, x, y);
Found it! the correct way of doing it is:
context.lineWidth = 3;
context.strokeStyle = "black";
context.strokeText(line, x, y);
context.fillStyle = "white";
context.fillText(line, x, y);
Don't forget the fillText after the stroke otherwise what you'll see is a very bold version of the text in the color of the stroke.
Related
I was trying to make a fullscreen window in OpenCV and the functions provided in OpenCV are working except there is a white edge in the left border and top border. After spending time in investigating the code in OpenCV, I found out that the function getWindowImageRect is somehow returning a value that is 1px more in x, y and 1px less in width and height than the function that I have wrote.
Okay, and here is the question. Why are the two functions returning different values?
Here is the code I have found in OpenCV:
CvRect cvGetWindowRect_W32(const char* name)
{
CvRect result = cvRect(-1, -1, -1, -1);
CV_FUNCNAME( "cvGetWindowRect_W32" );
__BEGIN__;
CvWindow* window;
if (!name)
CV_ERROR( CV_StsNullPtr, "NULL name string" );
window = icvFindWindowByName( name );
if (!window)
EXIT; // keep silence here
RECT rect;
GetClientRect(window->hwnd, &rect);
{
POINT pt = {rect.left, rect.top};
ClientToScreen(window->hwnd, &pt);
result = cvRect(pt.x, pt.y, rect.right - rect.left, rect.bottom - rect.top);
}
__END__;
return result;
}
This is the code that I have wrote in Python, which I thought will give me the same result:
def getWindowRect(name)
hwnd = win32gui.FindWindow(None, name)
rect_l, rect_t, rect_r, rect_b = win32gui.GetClientRect(hwnd)
pt_x, pt_y = win32gui.ClientToScreen(hwnd, (rect_l, rect_t))
result = (pt_x, pt_y, rect_r - rect_l, rect_b - rect_t)
return result
The result of using the two above functions give me output like this:
(1, 1, 2559, 1439)
(0, 0, 2560, 1440)
So I wonder if any one can tell me why is this happening?
Note that the test is performed under Windows 10.
I'm currently working on a program for character recognition using C# and AForge.NET and now I'm struggling with the processing of blobs.
This is how I created the blobs:
BlobCounter bcb = new BlobCounter();
bcb.FilterBlobs = true;
bcb.MinHeight = 30;
bcb.MinWidth = 5;
bcb.ObjectsOrder = ObjectsOrder.XY;
bcb.ProcessImage(image);
I also marked them with rectangles:
Rectangle[] rects;
rects = bcb.GetObjectsRectangles();
Pen pen = new Pen(Color.Red, 1);
Graphics g = Graphics.FromImage(image);
foreach (Rectangle rect in rects)
{
g.DrawRectangle(pen, rect);
}
After execution my reference image looks like this:
BlobImage
As you can see, almost all characters are recognized. Unfortunately, some character include blobs inside a blob, e.g. "g", "o" or "d".
I would like to eliminate the blobs which are inside another blob.
I tried to adjust the drawing of the rectangles to achieve my objective:
foreach (Rectangle rect in rects)
{
for (int i = 0; i < (rects.Length - 1); i++)
{
if (rects[i].Contains(rects[i + 1]))
rects[i] = Rectangle.Union(rects[i], rects[i + 1]);
}
g.DrawRectangle(pen, rect);
}
...but it wasn't successful at all.
Maybe some of you can help me?
you can try to detect rectangles within rectangles by check their corner indices,
I have one MATLAB code for this which i have written for similar kind of problem:
Here is snippet of the code is:
function varargout = isBoxMerg(ReferenceBox,TestBox,isNewBox)
X = ReferenceBox; Y = TestBox;
X1 = X(1);Y1 = X(2);W1 = X(3);H1 = X(4);
X2 = Y(1);Y2 = Y(2);W2 = Y(3);H2 = Y(4);
if ((X1+W1)>=X2 && (Y2+H2)>=Y1 && (Y1+H1)>=Y2 && (X1+W1)>=X2 && (X2+W2)>=X1)
Intersection = true;
else
`Intersection = false;`
end
Where X and Y are upper left corner indices of the bounding rectangle; W and H are width and height respectively.
in above if Intersection variable becomes true that means the boxes having intersection. you can use this code for further customization.
Thank You
I'm trying to achieve this kind of shadow, my research led me to using the CGPathRefto draw the shadow myself, but I can't figure out how it actually works.
Drawing the label.layer.shadowPath looks like a good plan, can anyone show me/point me to how I should proceed?
EDIT : I'm now to the point of trying to draw a UIBezierPath based on the string in the current label, the path being the actual shape of the shadow I need. I'm not sure that's the best option but it looks more promising.
EDIT 2 : Here is the code i'm now working with. this outlines the text of the label as an image, but it's pretty much the exact same text as the label itself, i still have to work my way around making it look like a shadow. Note, we're using Xamarin
public override void Draw (CoreGraphics.CGRect rect)
{
base.Draw (rect);
using (CGContext g = UIGraphics.GetCurrentContext ()) {
UIBezierPath completePath = UIBezierPath.Create ();
g.ScaleCTM (1, -1);
g.TranslateCTM (2, -(this.Bounds.Height / 2) - (this.Font.LineHeight / 3));
CTLine line = new CTLine (this.AttributedText);
CTRun[] runs = line.GetGlyphRuns ();
for (int i = 0; i < runs.Length; i++) {
CTRun run = runs [i];
CTFont font = run.GetAttributes ().Font;
for (int j = 0; j < run.GlyphCount; j++) {
NSRange currentRange = new NSRange (j, 1);
CGPoint[] positions = run.GetPositions (currentRange);
ushort[] glyphs = run.GetGlyphs (currentRange);
CGPath letter = font.GetPathForGlyph (glyphs [0]);
CGAffineTransform transform = CGAffineTransform.MakeTranslation (positions [0].X, positions [0].Y);
CGPath path = new CGPath (letter, transform);
UIBezierPath newPath = UIBezierPath.FromPath (path);
completePath.AppendPath (newPath);
}
}
completePath.LineWidth = 1;
UIColor.Red.SetStroke ();
UIColor.Blue.SetFill ();
completePath.Stroke ();
completePath.Fill ();
completePath.ClosePath ();
//Here I will try to loop over my current points and go down & right at every step of the loop, see how it goes performance-wise. Instead of one complex drawing I'll just have a very simple drawing that has thousands of points :o
g.AddPath (completePath.CGPath);
g.DrawPath (CGPathDrawingMode.FillStroke);
}
There is no built in way to achieve this effect. You have to implement the drawing code on your own.
Here are two ideas to create the shadow:
Draw the text in dark blue color, repeated n times, starting from the original position in 0.5 pt. steps shifted down right. This has bad performance but is really easy to implement.
Find the text outline using Core Text and implement some algorithm that creates the actual outline of the shadow. This could then be used as the shadowPath property.
I'm trying to make a simple app doing something similar to the Layer Spy Example, but instead of a circle flowing the mouse pointer, I would like to do the clipping based on a rectangle which is always centered in the map.
(preferably with "fixed" size" i.e. changes "extent" when zooming)
Any help appreciated
Thanks
Frode
You can do it like in the example that you are referring to. But instead of context.arc() use context.rect() with a fixed position to clip the layer. Something like:
imagery.on('precompose', function(event) {
var ctx = event.context;
var pixelRatio = event.frameState.pixelRatio;
ctx.save();
ctx.beginPath();
var x = ctx.canvas.width / 2 - 100;
var y = ctx.canvas.height / 2 - 100;
ctx.rect(x, y, 100, 100);
ctx.clip();
});
http://jsfiddle.net/eo1c1x78/
The issue of programmatically drawing lines using XNA has been covered here. However, I want to allow a user to draw on a canvas as one would with a drawing app such as MS Paint.
This of course requires each x and/or y coordinate change in the mouse pointer position to result in another "dot" of the line being drawn on the canvas in the crayon color in real time.
In the mouse move event, what XNA API considerations come into play in order to draw the line point by point? Literally, of course, I'm not drawing a line as such, but rather a sequence of "dots". Each "dot" can, and probably should, be larger than a single pixel. Think of drawing with a felt tip pen.
The article you provided suggests a method of drawing lines with primitives; vector graphics, in other words. Applications like Paint are mostly pixel based (even though more advanced software like Photoshop has vector and rasterization features).
Bitmap editor
Since you want it to be "Paint-like" I would definitely go with the pixel based approach:
Create a grid of color values. (Extend the System.Drawing.Bitmap class or implement your own.)
Start the (game) loop:
Process input and update the color values in the grid accordingly.
Convert the Bitmap to a Texture2D.
Use a sprite batch or custom renderer to draw the texture to the screen.
Save the bitmap, if you want.
Drawing on the bitmap
I added a rough draft of the image class I am using here at the bottom of the answer. But the code should be quite self-explanatory anyways.
As mentioned before you also need to implement a method for converting the image to a Texture2D and draw it to the screen.
First we create a new 10x10 image and set all pixels to white.
var image = new Grid<Color>(10, 10);
image.Initilaize(() => Color.White);
Next we set up a brush. A brush is in essence just a function that is applied on the whole image. In this case the function should set all pixels inside the specified circle to a dark red color.
// Create a circular brush
float brushRadius = 2.5f;
int brushX = 4;
int brushY = 4;
Color brushColor = new Color(0.5f, 0, 0, 1); // dark red
Now we apply the brush. See this SO answer of mine on how to identify the pixels inside a circle.
You can use mouse input for the brush offsets and enable the user to actually draw on the bitmap.
double radiusSquared = brushRadius * brushRadius;
image.Modify((x, y, oldColor) =>
{
// Use the circle equation
int deltaX = x - brushX;
int deltaY = y - brushY;
double distanceSquared = Math.Pow(deltaX, 2) + Math.Pow(deltaY, 2);
// Current pixel lies inside the circle
if (distanceSquared <= radiusSquared)
{
return brushColor;
}
return oldColor;
});
You could also interpolate between the brush color and the old pixel. For example, you can implement a "soft" brush by letting the blend amount depend on the distance between the brush center and the current pixel.
Drawing a line
In order to draw a freehand line simply apply the brush repeatedly, each time with a different offset (depending on the mouse movement):
Custom image class
I obviously skipped some necessary properties, methods and data validation, but you get the idea:
public class Image
{
public Color[,] Pixels { get; private set; }
public Image(int width, int height)
{
Pixels= new Color[width, height];
}
public void Initialize(Func<Color> createColor)
{
for (int x = 0; x < Width; x++)
{
for (int y = 0; y < Height; y++)
{
Pixels[x, y] = createColor();
}
}
}
public void Modify(Func<int, int, Color, Color> modifyColor)
{
for (int x = 0; x < Width; x++)
{
for (int y = 0; y < Height; y++)
{
Color current = Pixels[x, y];
Pixels[x, y] = modifyColor(x, y, current);
}
}
}
}