I have a form with a panel where a set of complex graphics are painted (represented by blue circles in the image):
The graphics are painted using DrawLine and DrawEllipse methods of the Graphics class.
I need to find the global center of the set of graphics (yellow point on the image) so that I can apply some transformations afterwards, like centering the set of graphics on the panel.
The most direct workaround I can think of is finding the boundaries of the graphics, so they are contained in a rectangular frame (red box on the image) and then divide the frame's width and height by two.
But how can I achieve this? Is there a method that would allow me to find the top, bottom, left and right boundaries of the entire set of graphics?
I'm not aware of any method in Graphics to do what you're looking for, but rolling your own should be relatively easy assuming you know the dimensions of each component image. The various DrawEllipse methods each take a bounding rectangle in some form, so you've already got all of the information that you need.
The most straightforward approach would be to simply keep track of the farthest left, right, top, and bottom bound of each image as you draw it and then form the complete bounding rectangle from those dimensions. You'll also need to account for the width of the Pen that you're using to draw your images.
As an alternative, you might want to take a look at the GraphicsPath class. GraphicsPath.GetBounds would more or less give you what you're looking for. If GraphicsPath doesn't work for you, then I think you're probably stuck writing your own code.
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
I've been learning how to draw lines in winforms apps, and I'd like to be able to select something (rectangle, for example) that has already been drawn by left clicking it, and then be able to move it around to another location by dragging it with the mouse.
How can this be done? I don't see any methods for this so I think I will need to figure out if there is anything where I left-click on the form, and if there is, then somehow figure out the dimensions of it and redraw it appropriately. Is this correct? And how would I know where the reactangle starts, where it ends, how heigh it is, what color(s) it has, and what if it's overlapping another line, rectangle or another shape?
I've not been able to find much on the System.Drawing namespace for things like this, and what I have found so far is just basic "How to draw lines" type stuff.
Your drawing is a bitmap, not a vectorial image. Basically, it's just lots of pixels. Once your rectangle is drawn, it's just some pixels, but the rectangle itself (with coordinates and size) doesn't exist anymore.
What you can do is saving data for every shape (in a List for example). Then, when you click on your image to select something, you test every object in your list in reverse order until the mouse coordinates are within your shape. Then, if, for example, you want to delete the shape, you remove the shape from your list, then you clear your image and redraw every shape in your list.
I am attempting to make a reusuable, XAML, icon. It is composed of three parts.
Background, Bezel and Graphic Path objects. The shape is of a rectangle with the top right corner cut off, the bezel is same shape with the middle cut out and a margin of 1.
I need the graphic path to fit inside of this with a slight margin.
I would like it to be intelligent enough to scale itself to fit within the confines of the bezel regardless of it's shape. Like ClipToBounds only I don't want the graphic to clip - I would like it to scale.
I initially thought setting the Margin would work, however, setting the Margin of the graphic is based on a Rectangle and not the irregular shape of the bezel; so graphics with a more rectangular shape are often touching or too close to the right-side cut off of the bezel.
Does anyone have any ideas on how I might achieve this kind of ScaleToBounds behavior?
EDIT:
Please see attached pictures for an example of the problem. Both graphics are contained inside a ViewBox with a Margin. The circular graphic is the ideal margin I would like to see around the graphic. The rectangular graphic is too close to the bezel - I would like to have graphics such as the rectangular graphic scale themselves down slightly so they fit within the bezel with some margin.
rectangular graphic http://s11.postimage.org/a5v05ve2n/rectangular.png
circular graphic http://s11.postimage.org/do7029eyn/circular.png
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 trying to make my UserControl with custom borders (I changed default border style to "none" in properties - I created control and I am invoking Graphics.DrawRectangle(...,ClientRectangle). And what I see is only the top and left borders of my painted rectangle - it seems that real size of the area where I can draw is different than ClientRectangle... How to change it / get the right ClientRectangle size?
ClientRectangle returns the rectangle in exclusive coordinates so you need to subtract 1 from the bottom and right hand sides. This will work regardless of how many units per pixel there are in the current graphics mode, someone correct me if I am wrong.