I know how to draw straight lines in C#, but I would like to draw a horizontal line, with two colors. Light blue on the top, and dark blue on the bottom. Also, how would I sort of... Append to that line? For example, every few seconds, that line will become bigger... like a ProgressBar. (btw, I'm not creating a ProgressBar, just using that as an example).
Here's the kind of line that I'd like to draw. I am aware that I can simply use PictureBox. But I want to start drawing!
Also, if there are other ways of drawing, than GDI or GDI+, could you list or link to those?
Thanks!
You can implement the onPaint event on any Control and then do the drawing manually on the passed graphics object.
Related
I am trying to do the following:
Open a new form and draw few lines and arcs (this is working well).
When an event occurs a new coordinate (x1,y1) is calculated, and a
small circle should be drawn at that coordinate.
When the next event occurs, a small circle should be drawn at
(x2,y2), and the first circle should disappear, while keeping the
lines and arcs that were drawn at step 1.
How do I delete the first circle while keeping all the rest?
Thank you
Once a circle has been drawn, there is no way to delete it. So, you need to clear the entire canvas with the background color and redraw everything.
So, you need to:
Come up with a bunch of "shape" classes for representing each line and each ark and each circle. They will probably all derive from some common base "Shape" class which offers methods that are common to all shapes, for example, a method to draw the shape on a canvas.
Instantiate objects from these classes to represent the shapes that are supposed drawn on the screen, and keep these objects in a list throughout the lifetime of your application.
When the event occurs, you make any changes to your shapes, (in your case, remove a circle and add another circle, or, more likely, change the coordinates of an existing circle without removing it and re-inserting it in the list,) and then you need to invalidate the canvas control that you presumably use for painting, (search for "Invalidate" for documentation,) so as to cause the canvas to repaint itself.
You override the paint method of the canvas control so as to do your painting: first you clear the control to its background color, and then you iterate through your list of shapes, calling each shape to draw itself on the canvas.
Of course this will cause flicker; if that's unacceptable, then you will need to read up on how to implement "double buffering" (look it up) to eliminate the flicker.
Another approach for flicker elimination is to only erase and repaint the area that has changed. In your case, that would be the smallest rectangle that contains both the circle in its old location, and the circle in its new location. So, instead of invalidating the entire canvas, you invalidate only that rectangle. The problem with this approach is that other shapes that cross the invalidated area might appear to be redrawn somewhat inaccurately. This may be unacceptable, or it may be acceptable, you will not know unless you try it.
You can't in the way you're thinking of, because the graphics works like MSPaint (a 2d array of pixels and when it's drawn, it's drawn) not Adobe Photoshop (layers or objects that can be moved independently)
The easiest thing to do is implement photoshop-like functionality yourself and keep eg a List of everything you want to draw, draw from the list (the list includes a circle) then later, remove that circle from the list, add another one and redraw the whole canvas from the list
I know it seems wasteful, and you probably could get into the mechanics of saving the pixels you drew over when you draw the first circle and restore them to erase the circle, but it's far more complex than just ditching it all and starting over every time
Is it possible to remove some lines in my graphic panel without erasing the rest?
PanelGraphics.Clear(Color.Black); erases all the graphics but I only want to remove one line, or a certain color.
Is this possible?
Is it possible to remove some lines in my graphic panel without erasing the rest?
Not really. The Graphics does not tell you anything about the actual context, it can be the screen, a printer, a bitmap, a metafile, the surface of a control or something similar. If you draw a Panel or a control you must always re-draw the whole content once it is invalidated. Otherwise, you will get a messy result. Just try to move your window partly out of the screen, the custom-drawn content will be "erased" unless you redraw it.
However, if you have a concrete image, such as a Bitmap, you can replace its colors; however, you must know the exact PixelFormat of the image. See my answer here if you are interested: https://stackoverflow.com/a/33562891/5114784
I want to write a GUI editor in C# for AutoIt, but I am not good enough with C#. I want to draw a square (focused) around an object when any object in the GUI is pressed. Like this:
Is there any library to make easier to write this kind of thing?
Square is drawn with one of DrawRectangle functions. Each of them requires a pen. Usually we use ordinary solid pen, but you need a pen with changed DashStyle property. For dotted lines change this property to DashStyle.Dot. You can also experiment with DashPattern property.
To draw little squares around the big square you need one of FillRectangle functions. Each of them requires a brush. You need a white brush, which is conveniently predefined for you to use. After filling a rectangle, you have to draw a rectangle over it with the same dimensions. These two functions together give an impression of empty and lined rectangle.
To make little squares a little rounded, like they are in the image, you have to change a pen parameter used when calling DrawRectangle. Experiment with LineJoin, and other properties of the Pen class.
This is very hard for a simple question that you posted. There are a lot of things that you need to take care of.
First I would suggest to make a class that will have a Rectangle property since you can't subclass Rectangle because it is a structure.
You will need to handle the drawing, that is the simplest task as mentioned in the other answers so I'm not going to be specific about that.
Since you have small squares that indicate that the rectangle can be resized, you will have to implement method that checks whether the mouse point is within the big rectangle or some of the small suqares. In this case you should change your cursor to indicate the possibility of resizing.
To handle moving (but not resizing) of the rectangle you will have either to make a new small square with the sign for moving in all directions or you will handle that using cursor when the mouse position is within the Big Rectangle.
The main problem is identifying what to change when resizing, you have two options:(1) to change Location and Size properties or to change X, Y, Width and (2)Height properties of the rectangle. For instance, when you are moving top-right corner you should change both Location and Size in first case or Y and Width is you are using second option.
When you move the mouse while it is clicked, you should watch out in which direction mouse moves. If you split the viewport in quadrants where the center of your rectangle is the center of the Decartes coordinate system, by identifying in which quadrant is the mouse you will know which corner (or edge) of the quadrant you need to move.
Each mouse move will have to call Invalidate() because you can't use Xor like in C++. Therefore, when your Rectangle is displayed, you should be in a special mode where everything that not moves (not changes, everything except Rectangle and selected control) should be drawn to the Bitmap that is used between two redraws and you should only draw what is moving.
As you can see, there is a lot of things that should be taken care of. You should start with this only after you are sure that you have already implemented other parts of your program.
I am a not very good at C# yet so bear with me,
I am trying to create a program that can edit pictures of small sizes (16x16, 32x32, etc...), specifically Minecraft texture files. I need to create a drawing surface where I can display rectangles on. I want to use WPF rectangles because they are working for me so far. I tried putting them on a WPF Grid panel but creating a good size grid panel with 1 pixel wide rows and columns takes about thirty seconds and that's quite a lot of time. Any ideas are helpful.
I'm getting the feel that your direction might not be the most efficient.
Of course, it's quite possible to convert an image into a lot of rectangles, but it's really not efficient once you have a lot of pixels. (32x32 = 1024 rectangles.)
So, instead of going along with WPF rectangles, like you want to, I would urge you to reconsider. Instead, try to work with WriteableBitmap.
From your vague description, I assume you are writing a paint like program, where the user can select a color and draw with the mouse on the texture with that color. By binding the WriteableBitmap up to an Image tag, and adding an event listener to the MouseMove event, you can get the mouse position, and whether the left/right mouse button is pressed or not. Combine that with some math involving the x position and the ActualWidth, and the y position and ActualHeight, of the Image, you can find the pixel the mouse is over, and set the color of that pixel.
So basically, Rectangles are not your best bet. Especially if you try to make a 32x32 grid to contain them. Use WriteableBitmap.
I would suggest using something more lightweight like DrawingVisuals. Alternatively if you really just want to display the textures you can preprocess them and display the result as a normal Image.
Imagine there's a picturebox which loads a monochrome image. And there is a need to make few color scribbles on it. I have no background with graphics. Would it be just a pen drawing pixels or something more complex I don't know.
Target language is C#. Technology: WinForms.
I think the easiest way to achieve what you want would be to create a very lightweight retained mode drawing system. Keep track of all the positions where the user has scribbeled and draw dots/circles/lines/rubberducks/whatever at these positions in the PictureBox's Paint event. On mousedown+move events, call the PictureBox' Invalidate() function. The original picture must either be painted underneath or in the class' OnPaintBackground (which IMO is more elegant).
This tutorial should get you started:
https://web.archive.org/web/20121006140255/http://www.bobpowell.net/backtrack.htm