ImageView

日本語

ImageView displays a UIng Image using a native image view. UIng accepts raw pixels and does not depend on an image decoder. Add CrImage to your application's shard.yml to use the optional image and color helpers:

dependencies:
  uing:
    github: kojix2/uing
  crimage:
    github: naqvis/crimage

require "uing/crimage"

source = CrImage.read("photo.png")
view = UIng::ImageView.new(source, :fit)
view.image = CrImage.read("next.png")

# For an Area, Table, or Toolbar, keep the native image until it is no longer used.
image = UIng::Image.from_crimage(source)
# ... use image ...
image.free

Runnable example

require "uing/crimage"

fname = File.join(__DIR__, "../gallery/crys.png")
source = CrImage.read(fname)

UIng.init

window = UIng::Window.new("ImageView Example", 300, 200, margined: true)
window.on_closing do
  UIng.quit
  true
end

vbox = UIng::Box.new(:vertical)

image_view = UIng::ImageView.new(source, :fit)

label = UIng::Label.new(fname)

vbox.append(image_view, stretchy: true)
vbox.append(label)

window.child = vbox
window.show

UIng.main
UIng.uninit

Usage notes

  • Use ContentMode::Fit to scale the image to fit the view, or ContentMode::Center to display it centered at its natural size.
  • Assign another Image with image=, or assign nil to clear the view.
  • ImageView copies or retains its own native image. The source Image can therefore be freed immediately after construction or assignment.
  • require "uing" works without CrImage; require "uing/crimage" adds the optional helpers. CrImage must be a dependency of the application using them.
  • UIng::Image.from_file(path) detects the format from file contents. CrImage.read(path) uses the filename extension in this CrImage version.
  • UIng::Image.from_crimage, CrImage::Image#to_uing_image, and UIng::Image#append(CrImage::Image) accept any CrImage image. The adapter converts pixels to premultiplied RGBA and handles nonzero image origins and subimages.
  • ImageView releases its temporary UIng image after assignment. Images returned by from_crimage, from_file, or to_uing_image must be freed by the caller after their consumers are done with them.
  • The same opt-in require adds CrImage color overloads for ColorButton#set_color, solid brushes, gradient stops, text attributes, and table color values. Use CrImage::Color::NRGBA for translucent UI colors. In the current CrImage version, Color.parse does not premultiply translucent RGBA correctly.

ImageView API · Image API · Gallery source