Chitra - 2D graphics library - D programming language

Hello Rectangle

import chitra;

void main()
{
    auto ctx = Chitra(700);
    with (ctx)
    {
        background(255);
        fill(0, 0, 255);
        rect(100, 100, 500, 200);
        saveAs("rect.png");
    }
}

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Install

Currently the Chitra project uses Cairo Graphics and Pango libraries. Once it gets the GIF and animation video creation capabilities, I will update the new dependencies here.

Ubuntu

sudo apt install libcairo2 libcairo2-dev libpango1.0-dev

Fedora

sudo yum install cairo-devel pango-devel

Mac

brew install cairo pango

Once the dependencies installed, add Chitra to your project by running

dub add chitra

Documentation

Canvas

Create the canvas to suit your requirement.

// Default size 700x700 pixels
auto ctx = new Chitra;
// Create a Square
auto ctx = new Chitra(800);

// Create a custom size in pixels
//                    w     h
auto ctx = new Chitra(1600, 900);

// Create with the required paper size
auto ctx = new Chitra("a4");
auto ctx = new Chitra("a4,landscape");

// By giving specific size in inch, cm, mm
auto ctx = new Chitra(10.inch, 5.inch);

Using the Canvas

Canvas context can be used in two ways

ctx.rect(100, 100, 500, 200);
ctx.saveAs("rect.png");

// OR using the with statement
with (ctx)
{
    rect(100, 100, 500, 200);
    saveAs("rect.png");
}

In this documentation, I will use the second method using with statement.

Properties

Width and Height

Access the width and height of the canvas.

rect(100, 100, width - 200, height - 200);

Background and Border

Fill the background with given color. Color can be provided in RGB, or Gray scale or hex strings. Background will draw a rectangle with canvas width and height.

// Black background. 0 - Black and 255 - White
background(0);
// Black background with 50% opacity
background(0, 0.5);

// Blue Background
background(0, 0, 255);

// Blue background with opacity 0.7
background(0, 0, 255, 0.7);

// Hex String
background("#9694FF");

// Or color names
background("blue");

Add border to canvas using,

// Black border of thickness 2
border;

// Border with margin
border(m: 10);
border(m: 10, mt: 0);

// Border with different color
border(m: 10, color: color("blue"));

// Border with radius
border(m: 10, color: color("blue"), r: 7);

Fill

Similar to background, specify the color before drawing a shape or the text. For example,

//   color
fill("red");
//   x    y    w    h
rect(100, 100, 500, 200);

To remove filling use noFill

noFill;
rect(100, 100, 500, 200);

Set the Fill opacity with color or set it seperately using fillOpacity

fill(0, 0, 255, 0.7);
// OR
fill(0, 0, 255);
fillOpacity(0.7);

Stroke

Similar to background and fill, specify the stroke color before drawing a shape or the text.

//     color
stroke("red");
noFill;
rect(100, 100, 500, 200);

To disable stroke, use noStroke and change the width of stroke using strokeWidth

// Draw a rectangle with red border, without fill
noFill;
stroke("red");
strokeWidth(2);
rect(100, 100, 500, 100);

// Draw a blue rectangle without the border
noStroke;
fill("blue");
rect(100, 210, 500, 100);

Set the Stroke opacity with color or set it seperately using strokeOpacity

stroke(0, 0, 255, 0.7);
// OR
stroke(0, 0, 255);
strokeOpacity(0.7);

Shapes

Pixel

Draw a single pixel on screen.

//   R  G  B
fill(0, 0, 255);
//    x    y
pixel(100, 100);

Rectangle

Draw a rectangle

//   x    y    w    h
rect(100, 100, 500, 200);

Square

Draw a square using rect or square function

rect(100, 100, 500);
// OR
square(100, 100, 500);

Draw a rounded rectangle.

//   x    y    w    h    Radius
rect(100, 100, 500, 200, r: 10);
// Only Top right border radius
rect(100, 100, 500, 200, rtr: 10);
// Similarly use, rtl, rbl, rbr to customize the respective border radius

Oval

Draw a Oval shape by giving width and height

//   x    y    w    h
oval(100, 100, 500, 200);

Circle

Draw a circle using oval or circle function

oval(100, 100, 500);
// OR
circle(100, 100, 500);

Point

Alias to circle.

// Default 2px point
point(100, 100);
point(100, 100, 10);

Polygon

Give all points in a array or give point pairs in a array to draw a polygon.

//       x1  y1   x2  y2  x3   y3  x4   y4    closePath
polygon([50, 450, 50, 50, 450, 50, 100, 100], true);
//        x1  y1     x2  y2    x3   y3    x4   y4     closePath
polygon([[50, 450], [50, 50], [450, 50], [100, 100]], true);

Line

Draw a line from one point to another point.

//   x1   y1   x2   y2
line(100, 100, 200, 200);

New Page and new drawing

While working with PDF documents, use newPage to create a new page.

fill("red");
rect(100, 100, width - 200, height - 200);
newPage;
fill("blue");
rect(100, 100, width - 200, height - 200);
saveAs("rects.pdf");

To clear the document and start the fresh canvas, use newDrawing

background(0);
saveAs("slide1.png");
newDrawing;
background(0, 0, 255);
saveAs("slide2.png");

Transformations

Rotate

Rotate the canvas.

//     angle in degrees
rotate(45);
rect(100, 100, 500, 200;

To rotate from the center of the rect,

//     angle  centerX  centerY
rotate(45,    350,     200);
rect(100, 100, 500, 200;

Scale

scale(2);
rect(100, 100, 500, 200);

To scale x and y seperately,

scale(2, 1);
rect(100, 100, 500, 200);

Translate

Translate the canvas to given x and y. This will become new origin for all the drawings.

translate(100, 100);
rect(0, 0, 500, 200);

This will be very useful to draw the complex shapes. Create the complex shape as a function and then call the function multiple times with different translate values.

PNG images

Add PNG image to the canvas using,

//    Path        x   y
image("logo.png", 50, 50);

To scale the image,

auto size = imageSize("logo.png");
auto requiredWidth = 300;
auto s = requiredWidth/size.width;
// Scale the canvas
scale(s);
// Draw the image
image("logo.png", 100/s, 100/s);
// Scale the canvas back to its original scale
scale(1/s);

Text

Set the properties and draw text using,

textFont("Inter", 20);
textColor("blue");
text("Hello World!", 100, 100);

Use FormattedString type to customize the text formatting. Below code is equivalant to the above code.

auto props = TextProperties(color: color("blue"), size: 20, font: "Inter");
auto t = FormattedString("Hello World!", props);
text(t, 100, 100);

Adding text and more formatting is very simple. For example,

auto h1Style = TextProperties(size: 24.88, namedWeight: TextNamedWeight.bold, color: color(0));
auto parStyle = TextProperties(size: 12, color: color(0));

alias FS = FormattedString;

FS sample;
sample ~= FS("Hello World!\n", h1Style);
sample ~= FS("This is a paragraph\n", parStyle);

text(sample, 100, 100);

Export/Save

PDF, PNG and SVG output formats are supported.

saveAs("rect.png");
saveAs("rect.pdf");
saveAs("rect.svg");

Set resolution

saveAs("rect.png", resolution: 300);
saveAs("rect.pdf", resolution: 300);
saveAs("rect.svg", resolution: 300);

Thanks

• Cairo Graphics
• Drawing API syntax are inspired from Drawbot and Processing.

Contributing

• Fork it (https://github.com/aravindavk/chitra-d/fork)
• Create your feature branch (git checkout -b my-new-feature)
• Commit your changes (git commit -am 'Add some feature')
• Push to the branch (git push origin my-new-feature)
• Create a new Pull Request

Contributors

• Aravinda VK - Creator and Maintainer