Drawing over a 3D rendered scene using C# - c#

UPDATE: Since originally asking this question, I have changed my approach slightly. Rather than drawing using System.Drawing.Graphics, I am hosting a WPF user control with an InkCanvas. That does everything I need it to do. The problem still is that I cannot get the background of the ElementHost to be transparent. I see the same black square I was seeing before.
ORIGINAL QUESTION: I have a C# WinForms application that renders a 3D scene using Ogre3D to a panel in the form using that panel's handle. I am trying to add the ability to draw on top of that scene (imagine Madden drawing over the TV screen) using C#'s System.Drawing.Graphics.
I'm using the BufferedGraphics class to do this. As a test, I'm trying to simply draw a rectangle on top of the 3D scene. Below is a snippet of the code I'm using to set everything up.
namespace TestApp
{
public partial class TestForm
{
private BufferedGraphics graphicsBuffer;
private BufferedGraphicsContext bufferContext = BufferedGraphicsManager.Current;
public TestForm()
{
InitializeComponent();
UpdateGraphicsBuffer();
}
private void UpdateGraphicsBuffer()
{
bufferContext.MaximumBuffer = new Size(panelRender.Width + 1, panelRender.Height + 1);
graphicsBuffer = bufferContext.Allocate(Graphics.FromHwnd(panelRender.Handle), new Rectangle(49, 49, 100, 100));
graphicsBuffer.Graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
}
private void TestForm_Load(object sender, EventArgs e)
{
graphicsBuffer.Graphics.DrawRectangle(new Pen(Color.Red), 50, 50, 50, 50);
}
}
}
I've left out a lot of the proprietary code (there is a call to graphicsBuffer.Render(); in part of that proprietary code) and renamed some stuff but hopefully what I have provided will give you the gist. Also, the 3D scene is also using panelRender.Handle to draw into that panel, and the panelRender.BackColor is black.
In a nutshell, what I am seeing is a chunk of my 3D scene missing (specifically a 100x100 chunk) with the 50x50 red rectangle drawn inside it, as pictured here:
Obviously I don't want to lose the scene that I'm trying to draw on top of. Right now, I'm at a loss as to why this is happening. Is what I'm trying to do just not possible? If any additional information/code is needed, I will be happy to provide it, if possible.
EDIT:
To try and simplify matters, I created a really simple WinForms app that has a single panel and used the code above to recreate the issue. The code-behind for that is here:
using System.Drawing;
using System.Windows.Forms;
namespace DoubleBufferTest
{
public partial class Form1 : Form
{
private BufferedGraphics graphicsBuffer = null;
private BufferedGraphicsContext bufferContext = BufferedGraphicsManager.Current;
public Form1()
{
this.SetStyle(ControlStyles.SupportsTransparentBackColor | ControlStyles.UserPaint, true);
this.UpdateStyles();
InitializeComponent();
UpdateGraphicsBuffer();
}
private void UpdateGraphicsBuffer()
{
bufferContext.MaximumBuffer = new Size(panel1.Width + 1, panel1.Height + 1);
graphicsBuffer = bufferContext.Allocate(Graphics.FromHwnd(panel1.Handle), new Rectangle(10, 10, 50, 50));
}
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
graphicsBuffer.Graphics.DrawRectangle(new Pen(Color.Red, 3.0f), 20, 20, 10, 10);
graphicsBuffer.Render();
}
}
}
The panel's backcolor is set to transparent. Here is the result:
That black square corresponds to the graphics buffer that is getting allocated by the context. Why it always shows up as black is basically what is confusing me now...

Thank you to #Ron Beyer for answering this for me in a different question I posted.
So I was on the right track with the ElementHost control, but because of the transparency issues, Ron suggested that I try using a new WPF window that I could overlay on top of the application (link). The WPF window's background is set to transparent, so drawing on the InkCanvas results in the desired effect.

Related

Getting a line that has the coordinates defined by the mouse location

I'm trying to make a little graphics program that has a circle of diameter 100 on the screen and from the center of it, a line is coming out of it that is always attached to the mouse pointer until such time that the user does a click, and then the line is permanently drawn. It's exactly like MSPaint's line, except that starting point is always the center of the circle.
I tried a few things that DON'T work.
I can get the line to appear only after a mouse-click. That's not what I want. I want the line to always be present and pivoting from the circle-center until the mouse is clicked and then it's then permanently on the screen.
I can get a smeary thing where the line is always being drawn. It makes a sort of star shape, but that's not what I want either.
Basically, I want the same functionality that you have in MSPaint when you draw a line. What am I supposed to do? Draw the line and then erase it a second later, and then draw it again when the mouse is in a new position? I tried something like that, but it does a thing where it erases the background a little bit, and then the line is only drawn when the mouse is in motion, but not when the mouse is stationary.
If anyone can provide a code snippet, that'd be great. Or just some pseudo-code.
Is this the right pseudo code?
Start:
Left click and a line appears from center of circle to mouse tip
Line stays there until a new mouse coordinate is made (how do I keep track)?
Line from center of circle to original location gets erased
New line is made to new location of mouse coordinates.
I think this something of a state-machine to use what I learned in digital class. How are states implemented in C#?
Any help would be appreciated, and thanks to everyone that can understand my question even though I'm probably not using the proper terminology.
So short answer is you will need some custom painting. The longer answer involves custom drawing, and event handling.
The other piece of code you need is a list of some sort to hold all of the lines. The code below creates a user control and does the custom painting without relying on a state machine. To test it, create a new project add a user control called UserControl1, and add it to a form. Make sure you tie into the listed events.
I tried to comment the relevant sections and this shows a quick and dirty way to do what you appear to be trying to do.
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;
namespace CustomDrawingAndEvents
{
public partial class UserControl1 : UserControl
{
private struct MyLine
{
public Point mStart;
public Point mEnd;
public MyLine(Point xStart, Point xEnd)
{
mStart = xStart;
mEnd = xEnd;
}
}
private List<MyLine> mLines;
private Point mCircleCenter;
private Point mMousePosition;
public UserControl1()
{
InitializeComponent();
mLines = new List<MyLine>();
//Double Buffer to prevent flicker
DoubleBuffered = true;
//Create the center for our circle. For this just put it in the center of
//the control.
mCircleCenter = new Point(this.Width / 2, this.Height / 2);
}
private void UserControl1_MouseClick(object sender, MouseEventArgs e)
{
//User clicked create a new line to add to the list.
mLines.Add(new MyLine(mCircleCenter, e.Location));
}
private void UserControl1_MouseMove(object sender, MouseEventArgs e)
{
//Update mouse position
mMousePosition = e.Location;
//Make the control redraw itself
Invalidate();
}
private void UserControl1_Paint(object sender, PaintEventArgs e)
{
//Create the rect with 100 width/height (subtract half the diameter to center the rect over the circle)
Rectangle lCenterRect = new Rectangle(mCircleCenter.X - 50, mCircleCenter.Y - 50, 100, 100);
//Draw our circle in the center of the control with a diameter of 100
e.Graphics.DrawEllipse(new Pen(Brushes.Black), lCenterRect);
//Draw all of our saved lines
foreach (MyLine lLine in mLines)
e.Graphics.DrawLine(new Pen(Brushes.Red), lLine.mStart, lLine.mEnd);
//Draw our active line from the center of the circle to
//our mouse location
e.Graphics.DrawLine(new Pen(Brushes.Blue), mCircleCenter, mMousePosition);
}
}
}

Which is faster when animating the UI: a Control or a Picture?

/I'm working with and testing on a computer that is built with the following:
{1 GB RAM (now 1.5 GB), 1.7 GHz Intel Pentium Processor, ATI Mobility Radeon X600 GFX}
I need scale / transform controls and make it flow smoothly. Currently I'm manipulating the size and location of a control every 24-33ms (30fps), ±3px. When I add a 'fade' effect to an image, it fades in and out smoothly, but it is only 25x25 px in size. The control is 450x75 px to 450x250 px in size. In 2D games such as Bejeweled 3, the sprites animate with no choppy animation.
So as the title would suggest: which is easier/faster on the processor: animating a bitmap (rendering it to the parent control during animation) or animating the control it's self?
EDIT:
Hey, I thought this was a helpful community, not one that down-rates questions that don't seem challenging! (And I've seen more ridiculous questions here with better ratings too!) Please drop me a line first before negatively rating my questions!
I managed to find some free-time in my heck-tick scheduled, to quickly whip up a new project. I'm sure my time could have been better spent else where but hopefully someone else in my shoes may find this of use out there...
The answer is: a Picture over a Control. When rendering a bitmap onto the canvas, there are very little events that will fire, if any. As for the control, it is filled with events - some chained, some looped, and the addition of recursion, so a simple 'LocationChanged' event wouldn't even cover the half of what actually is taking place under the hood.
What I would do for controls that have lots of dynamic animations applied to them during runtime, is to develop a two piece set: a control [rendering] template or active interface (for when the control is at a stand-still or before the play of an animation), and a the animating structure with basic defining properties such as the display image [the rendered control], the rectangle bounds, and any animation algorithms that may be applied latter.
Edit: As Requested, here are the before and after code examples:
// This is the triggering event of the translating animation
private void object_Click(object sender, EventArgs e)
{
// the starting point is at (75,75)
element.Transform(new Point(500, 250));
}
Before:
public class ControlElement : UserControl
{
private Timer tick;
private Point pT0;
public ControlElement() : base()
{
tick = new Timer();
tick.Interval = 30; // about 30fps
tick.Tick += new EventHandler(tick_Tick);
}
void tick_Tick(object sender, EventArgs e)
{
// get the new point from distance and current location/destination
this.Location = Utils.Transform(this.Location, pT0, 3);
if ((pT0.X - this.Location.X)+(pT0.Y - this.Location.Y) <= 0)
{
this.Location = pT0;
tick.Stop();
//this.Visible = true;
}
}
public void Transform(Point destination)
{
pT0 = destination;
//this.Visible = false;
tick.Start();
}
}
After: I create a class that holds a picture of what the control would look like using the DrawToBitmap feature. It still contains the same animation methods as above. I had to add the Location and LocationChanged elements since this class was no longer a control. If and when the actual control needed to be accessed, I would stop rendering and display an instance of the control it's self.
Here is the rendering call:
void element_LocationChanged(object sender, EventArgs e)
{
canvas.Invalidate();
}
void canvas_Paint(object sender, PaintEventArgs e)
{
if (element != null)
{
Bitmap bmp = new Bitmap(element.Display);
Pen p = new Pen(Color.FromArgb(128, 128, 128), 1);
e.Graphics.DrawImage(bmp, element.Location);
e.Graphics.DrawRectangle(p,
element.Location.X, element.Location.Y,
bmp.Width, bmp.Height);
}
}

Winform not scrolling when drawing objects on it

C#3.0,.net framework 3.5
I am drawing ( using the draw method in the graphics class) a lot of solid rectangles on a windows form vertically. The form starts at 500 x 500 px and the rectangles are only drawn at runtime after data is downloaded from the net -and the number of rectangles depends on the download so I do not know it upfront.
So only a few rectangles are drawn as the size of the form is fixed.
So I googled/Binged ( lest someone suggest I do that) and found a few tips but they don't work in this case -like setting the forms AutoScroll property to true or trying double buffering.I also tried to draw on a listbox control and set it's scroll property etc...but no dice.
I'm guessing there is no way to display , say 200 rectangles vertically on a windows form using draw. I need some other solution... any ideas please.
Maybe a list of pictureboxes and then populate each picturebox with the solid color ?
Thanks
You are drawing GDI+ rectangles on a form during the paint event? The form would have no idea that you are creating objects outside of the clipping space and would therefore have no idea that you need to scroll.
You would need to add a scrollbar to the form and then calculate the value\position of the scrollbar and use that to determine what portion of your rectangles to draw upon the paint event. This would involve a bit of manual effort. You could draw them all to an in-memory bitmap of the appropriate size and then just copy the portions of that to the form upon draw.
Or:
If you wanted the form to do this for you, create a custom rectangle control and place 200 of those on the form. Since they are components and have a concrete height & width, the form would then know it needed to scroll, and would do so accordingly provided that autoscroll was set.
it can be as simple as this:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
this.DoubleBuffered = true;
this.AutoScroll = true;
for (int i = 0; i < 100; i++)
this.Controls.Add(new Rectangle() { Top = i * 120, Left = 10 });
}
}
public class Rectangle : Control
{
public Rectangle()
{
this.Width = 100;
this.Height = 100;
}
protected override void OnPaint(PaintEventArgs e)
{
e.Graphics.DrawRectangle(new Pen(Color.Black, 5), 0, 0, 100, 100);
}
}

PictureBox resize & paint problem

I want to show some graphics in a Winform app, it will be a stock's chart drawing tool. I think (but I am not sure...) I have to use a PictureBox, and using the System.Drawing.Graphics class' drawing primitives to draw the chart. I have started coding it, now it works more-or-less, but I have a problem with the resizing feature, as follows: when I resize the entire form, I see that the program shows the graphics then inmediately clear it. When I stop the mouse movement (without to release the mouse button) the graphics disappears!?!?
I made a small test environment to demo the bug:
Using VS2005, creating a new C# Windows Forms app, adding only a PictureBox to the form.
Setting the PictureBox's anchor to left, top, right and bottom. Add two event handler, the Resize to the PictureBox, and the Paint to the Form.
namespace PictureBox_Resize {
public partial class Form1 : Form {
public Form1() {
InitializeComponent();
Ellipse_Area = this.pictureBox1.Size;
}
private Pen penBlack = new Pen(Color.Black, 1.0f);
private Size Ellipse_Area;
private void Form1_Paint(object sender, PaintEventArgs e) {
Graphics g = this.pictureBox1.CreateGraphics();
g.DrawEllipse(penBlack, 0, 0, Ellipse_Area.Width, Ellipse_Area.Height);
}
private void pictureBox1_Resize(object sender, EventArgs e) {
Control control = (Control)sender;
Ellipse_Area = control.Size;
this.pictureBox1.Invalidate();
}
}
}
This small app shows the problem. It only draws an ellipse, but of course my drawing code is much more complicated one...
Any idea why the ellipse disappears when I resize the Form????
Why are you using a PictureBox? I would create a UserControl for your chart and draw the ellipse in its Paint method, just using its current size. In its constructor, set it up for double buffering and all painting in the paint method.
this.SetStyle(ControlStyles.DoubleBuffer |
ControlStyles.UserPaint |
ControlStyles.AllPaintingInWmPaint,
true);
As far as I remember from my C++ days - where I did loads of such image-stuff - you need to call the repaint method - or override it to fit it for your behaviour.

Draw an ellipse without OnPaint method

I was looking about some GDI tutorial but everything I have found so far works with OnPaint method, which passes Paintarguments to Graphics. I have not found how to start from scratch, I mean how to use Graphics class itself?
This is the whole code I have treid that just doesnt work for me:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
Pen pen= new Pen(Color.Red, 3);
Graphics g;
g = this.CreateGraphics();
g.DrawEllipse(pen, 150, 150, 100, 100);
}
}
}
It just doesnt do anything. I tried it in new form, nothing.
Thank you in advance!
The code is probably OK, it is drawing a ellipse as you are hoping for. However, after the Load event, there will be a PaintBackground event and a PaintEvent as the form is displayed. The PaintBackground will, by default, erase the contents of the control, effectively removing the ellipse you've just drawn.
Painting is a two stage process:
for each (region in set of regions that need updating)
{
PaintBackground (region)
Paint (region)
}
The window manager only redraws the parts of the control that require updating, if the contents of the control haven't changed or no user action has altered the control's visibility then no painting is done.
So, why do you want to draw the ellipse in the Load method? Usually, you only want to draw something when something needs to be drawn, and your form is told when something needs drawing in the PaintBackground and Paint events.
Are you worried about flickering? Or is it a speed issue? Ellipses are quick to draw. Flickering, however, is harder to fix. You need to create a bitmap, draw to the bitmap and blit the bitmap to the control during the Paint event. Also, make the PaintBackground event do nothing - no erasing the control, it's the erasing that causes the flicker.
EDIT: An example, I'm using DevStudio 2005 here.
Create a new C# winform application.
In Form1.cs add the following:
protected override void OnPaintBackground (PaintEventArgs e)
{
// do nothing! prevents flicker
}
protected override void OnPaint (PaintEventArgs e)
{
e.Graphics.FillRectangle (new SolidBrush (BackColor), e.ClipRectangle);
Point
mouse = PointToClient (MousePosition);
e.Graphics.DrawEllipse (new Pen (ForeColor), new Rectangle (mouse.X - 20, mouse.Y - 10, 40, 20));
}
protected override void OnMouseMove (MouseEventArgs e)
{
base.OnMouseMove (e);
Invalidate ();
}
Compile and run.

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