58 lines
1.7 KiB
Go
58 lines
1.7 KiB
Go
// 21 august 2018
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package ui
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import (
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"image"
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)
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// #include "pkgui.h"
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import "C"
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// Image stores an image for display on screen.
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//
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// Images are built from one or more representations, each with the
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// same aspect ratio but a different pixel size. Package ui
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// automatically selects the most appropriate representation for
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// drawing the image when it comes time to draw the image; what
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// this means depends on the pixel density of the target context.
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// Therefore, one can use Image to draw higher-detailed images on
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// higher-density displays. The typical use cases are either:
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//
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// - have just a single representation, at which point all screens
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// use the same image, and thus uiImage acts like a simple
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// bitmap image, or
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// - have two images, one at normal resolution and one at 2x
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// resolution; this matches the current expectations of some
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// desktop systems at the time of writing (mid-2018)
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//
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// Image allocates OS resources; you must explicitly free an Image
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// when you are finished with it.
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type Image struct {
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i *C.uiImage
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}
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// NewImage creates a new Image with the given width and
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// height. This width and height should be the size in points of the
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// image in the device-independent case; typically this is the 1x size.
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func NewImage(width, height float64) *Image {
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return &Image{
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i: C.uiNewImage(C.double(width), C.double(height)),
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}
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}
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// Free frees the Image.
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func (i *Image) Free() {
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C.uiFreeImage(i.i)
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}
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// Append adds the given image as a representation of the Image.
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func (i *Image) Append(img *image.NRGBA) {
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cpix := C.CBytes(img.Pix)
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defer C.free(cpix)
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C.uiImageAppend(i.i, cpix,
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C.int(img.Rect.Dx()),
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C.int(img.Rect.Dy()),
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C.int(img.Stride))
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}
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