C#•8mo ago

✅ How can I draw a line between labels?

I have to draw lines between city labels. But when the form loads, the labels disappear and there is no line. What can I do?

66 Replies

TheRanger•8mo ago

I think you need to get the image's graphics, not create a new one

using (Graphics g = Graphics.FromImage(pictureBox1.Image))
{
    g.DrawLine(......
}

using (Graphics g = Graphics.FromImage(pictureBox1.Image))
{
    g.DrawLine(......
}

ʙʀʊʍɨOP•8mo ago

i just noticed this error

TheRanger•8mo ago

Those are warnings, not errors!

ʙʀʊʍɨOP•8mo ago

oh yea warning sorry :when: either way, im thinking that maybe i have to make the image some kind of grid so that i can give x,y,a,b some coordinates but idrk how to do that

TheRanger•8mo ago

a,b ?

ʙʀʊʍɨOP•8mo ago

for the two points i was thinking i couldn't use X and Y cuz they are the coordinates for the first point

TheRanger•8mo ago

What do you see now in your program?

ʙʀʊʍɨOP•8mo ago

in the form?

TheRanger•8mo ago

yes

ʙʀʊʍɨOP•8mo ago

its just the map the picture the labels disappeared and there's no line

TheRanger•8mo ago

disappeared? so they appeared at some point before they disappeared?

ʙʀʊʍɨOP•8mo ago

in the form they are there but once it runs they disappear

TheRanger•8mo ago

you mean the form builder?

ʙʀʊʍɨOP•8mo ago

its the first time im working with graphics so idk what to do the designer yea

TheRanger•8mo ago

the image is probably hiding the labels try calling .BringToFront() Method on the labels

ʙʀʊʍɨOP•8mo ago

I'll try

TheRanger•8mo ago

Graphics also has a method called DrawString You can draw text directly into the image also it looks to me like you're resetting the label's location to 0, 0 which is the top left coordinate of the form assuming x, y, a, b values are 0

ʙʀʊʍɨOP•8mo ago

ooh yea that makes sense the warnings do say they assign the value 0 yup they're in the top left corner so the first problem would be the location on the axis... alright so i managed to make them appear in the desired positions just copied their coordinates from the designer but the line still isn't there

TheRanger•8mo ago

what code are you using to try to draw a line?

ʙʀʊʍɨOP•8mo ago

i have to make it so the line appears when i press the button

TheRanger•8mo ago

do you know what Form2_Paint does? or when does it get called?

ʙʀʊʍɨOP•8mo ago

last time i used it it made a drawing when the form loaded

TheRanger•8mo ago

well, put this code in the button1_click then

using (Graphics g = Graphics.FromImage(pictureBox1.Image))
{
    g.DrawLine(......
}

using (Graphics g = Graphics.FromImage(pictureBox1.Image))
{
    g.DrawLine(......
}

also according to this code ur trying to draw the line on the form itself not on the image

ʙʀʊʍɨOP•8mo ago

ooh well not even with this change it doesnt show but i dont get any errors or warnings

TheRanger•8mo ago

show your new code

ʙʀʊʍɨOP•8mo ago

im still thinking it might be sum related to those integers

TheRanger•8mo ago

whats ur pictureBox called, is it pictureBox1 ?

ʙʀʊʍɨOP•8mo ago

yea

TheRanger•8mo ago

you sure you clicked the correct button?

ʙʀʊʍɨOP•8mo ago

yea well now i used left and top for the labels i had used .Location.X and .Location.Y before

TheRanger•8mo ago

i think you need to call pictureBox1.Invalidate(); to redraw the picturebox or .Refresh()

ʙʀʊʍɨOP•8mo ago

yup invalidate worked but the lines is not where it should be

ʙʀʊʍɨOP•8mo ago

it should be between these two labels

TheRanger•8mo ago

Yeah the labels are using the coordinates of the form while the line is using the coordinates of the image itself 1 minute

ʙʀʊʍɨOP•8mo ago

maybe if i make the form background the image?

TheRanger•8mo ago

there is a better way

ʙʀʊʍɨOP•8mo ago

lets hear it

TheRanger•8mo ago

PictureBox has a method called PointToClient where it translates a coordinate in the image into the form's coordinate you could try using that

ʙʀʊʍɨOP•8mo ago

how do i use it :when: i genuinely never heard of this method

TheRanger•8mo ago

https://learn.microsoft.com/en-us/dotnet/api/system.windows.forms.control.pointtoclient?view=windowsdesktop-8.0#system-windows-forms-control-pointtoclient(system-drawing-point)

Control.PointToClient(Point) Method (System.Windows.Forms)

Computes the location of the specified screen point into client coordinates.

ʙʀʊʍɨOP•8mo ago

like this?

TheRanger•8mo ago

use pictureBox1 instead of this

ʙʀʊʍɨOP•8mo ago

this refers to the form right?

TheRanger•8mo ago

yes

ʙʀʊʍɨOP•8mo ago

didnt work its even worse now

TheRanger•8mo ago

what do u mean?

ʙʀʊʍɨOP•8mo ago

TheRanger•8mo ago

yeah well i was gonna tell you to actually use the image coordinates for the labels

ʙʀʊʍɨOP•8mo ago

so... no more x and y? or what

TheRanger•8mo ago

Point contains x and y you can actually change x and y into Point to be stored into a single variable this code might work

private Point ConvertLabelPositionToImageCoordinates(Label label)
{
    // Ensure the PictureBox has an image
    if (pictureBox1.Image == null)
        return Point.Empty; // or throw an exception, depending on your requirements

    // Calculate the scaling factors for X and Y dimensions
    float scaleX = (float)pictureBox1.Image.Width / pictureBox1.ClientSize.Width;
    float scaleY = (float)pictureBox1.Image.Height / pictureBox1.ClientSize.Height;

    // Translate the label's position from the form coordinates to the PictureBox coordinates
    Point labelLocationPictureBox = pictureBox1.PointToClient(label.Parent.PointToScreen(label.Location));

    // Translate the PictureBox coordinates to the image coordinates
    int imageX = (int)(labelLocationPictureBox.X * scaleX);
    int imageY = (int)(labelLocationPictureBox.Y * scaleY);

    return new Point(imageX, imageY);
}

private Point ConvertLabelPositionToImageCoordinates(Label label)
{
    // Ensure the PictureBox has an image
    if (pictureBox1.Image == null)
        return Point.Empty; // or throw an exception, depending on your requirements

    // Calculate the scaling factors for X and Y dimensions
    float scaleX = (float)pictureBox1.Image.Width / pictureBox1.ClientSize.Width;
    float scaleY = (float)pictureBox1.Image.Height / pictureBox1.ClientSize.Height;

    // Translate the label's position from the form coordinates to the PictureBox coordinates
    Point labelLocationPictureBox = pictureBox1.PointToClient(label.Parent.PointToScreen(label.Location));

    // Translate the PictureBox coordinates to the image coordinates
    int imageX = (int)(labelLocationPictureBox.X * scaleX);
    int imageY = (int)(labelLocationPictureBox.Y * scaleY);

    return new Point(imageX, imageY);
}

Note i can't test, so i have to rely on your tests

ʙʀʊʍɨOP•8mo ago

ill see what i can do

TheRanger•8mo ago

code updated.. your label positions should be as it was as it was in this image and use this method to convert the label's position into the position in the image

ʙʀʊʍɨOP•8mo ago

alright lemme try

TheRanger•8mo ago

using (Graphics g = Graphics.FromImage(pictureBox1.Image))
{
    Pen p = new Pen(Color.Black, 3);
    Point from = ConvertLabelPositionToImageCoordinates(constLbl);
    Point to = ConvertLabelPositionToImageCoordinates(sochiLbl);
    g.DrawLine(p, from, to);
}

using (Graphics g = Graphics.FromImage(pictureBox1.Image))
{
    Pen p = new Pen(Color.Black, 3);
    Point from = ConvertLabelPositionToImageCoordinates(constLbl);
    Point to = ConvertLabelPositionToImageCoordinates(sochiLbl);
    g.DrawLine(p, from, to);
}

ʙʀʊʍɨOP•8mo ago

IT WORKED gad dayum

TheRanger•8mo ago

show 😄

ʙʀʊʍɨOP•8mo ago

TheRanger•8mo ago

Nice

ʙʀʊʍɨOP•8mo ago

thing is this saturday im gonna go to some kind of contest and idrk what subjects imma have but im gonna have to make an app like this not necesasrily like this one exactly but how can I remember all this

TheRanger•8mo ago

$practice

MODiX•8mo ago

https://cdn.discordapp.com/attachments/569261465463160900/1017547808611508234/unknown.png

ʙʀʊʍɨOP•8mo ago

true either way thank you so so much

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✅ How can I draw a line between labels?