ebiten/image.go

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// Copyright 2014 Hajime Hoshi
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
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package ebiten
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import (
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"errors"
"fmt"
"image"
"image/color"
"runtime"
"github.com/hajimehoshi/ebiten/internal/graphics"
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)
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// Image represents an image.
// The pixel format is alpha-premultiplied.
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// Image implements image.Image.
type Image struct {
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framebuffer *graphics.Framebuffer
texture *graphics.Texture
pixels []uint8
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width int
height int
}
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// Size returns the size of the image.
func (i *Image) Size() (width, height int) {
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if i.width == 0 {
i.width, i.height = i.framebuffer.Size()
}
return i.width, i.height
}
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// Clear resets the pixels of the image into 0.
func (i *Image) Clear() (err error) {
if i.isDisposed() {
return errors.New("image is already disposed")
}
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return i.Fill(color.Transparent)
}
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// Fill fills the image with a solid color.
func (i *Image) Fill(clr color.Color) (err error) {
if i.isDisposed() {
return errors.New("image is already disposed")
}
i.pixels = nil
return i.framebuffer.Fill(glContext, clr)
}
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// DrawImage draws the given image on the receiver image.
//
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// This method accepts the options.
// The parts of the given image at the parts of the destination.
// After determining parts to draw, this applies the geometry matrix and the color matrix.
//
// Here are the default values:
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// ImageParts: (0, 0) - (source width, source height) to (0, 0) - (source width, source height)
// (i.e. the whole source image)
// GeoM: Identity matrix
// ColorM: Identity matrix (that changes no colors)
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//
// Be careful that this method is potentially slow.
// It would be better if you could call this method fewer times.
func (i *Image) DrawImage(image *Image, options *DrawImageOptions) (err error) {
if i.isDisposed() {
return errors.New("image is already disposed")
}
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if i == image {
return errors.New("Image.DrawImage: image should be different from the receiver")
}
i.pixels = nil
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if options == nil {
options = &DrawImageOptions{}
}
parts := options.ImageParts
if parts == nil {
// Check options.Parts for backward-compatibility.
dparts := options.Parts
if dparts != nil {
parts = imageParts(dparts)
} else {
w, h := image.Size()
parts = &wholeImage{w, h}
}
}
w, h := image.Size()
quads := &textureQuads{parts: parts, width: w, height: h}
return i.framebuffer.DrawTexture(glContext, image.texture, quads, &options.GeoM, &options.ColorM)
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}
// Bounds returns the bounds of the image.
func (i *Image) Bounds() image.Rectangle {
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w, h := i.Size()
return image.Rect(0, 0, w, h)
}
// ColorModel returns the color model of the image.
func (i *Image) ColorModel() color.Model {
return color.RGBAModel
}
// At returns the color of the image at (x, y).
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//
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// This method loads pixels from VRAM to system memory if necessary.
func (i *Image) At(x, y int) color.Color {
if i.isDisposed() {
return color.Transparent
}
if i.pixels == nil {
var err error
i.pixels, err = i.framebuffer.Pixels(glContext)
if err != nil {
panic(err)
}
}
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w, _ := i.Size()
w = int(graphics.NextPowerOf2Int32(int32(w)))
idx := 4*x + 4*y*w
r, g, b, a := i.pixels[idx], i.pixels[idx+1], i.pixels[idx+2], i.pixels[idx+3]
return color.RGBA{r, g, b, a}
}
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// Dispose disposes the image data. After disposing, the image becomes invalid.
// This is useful to save memory.
//
// The behavior of any functions for a disposed image is undefined.
func (i *Image) Dispose() error {
if i.isDisposed() {
return errors.New("image is already disposed")
}
if i.framebuffer != nil {
i.framebuffer.Dispose(glContext)
i.framebuffer = nil
}
if i.texture != nil {
i.texture.Dispose(glContext)
i.texture = nil
}
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i.pixels = nil
runtime.SetFinalizer(i, nil)
return nil
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}
func (i *Image) isDisposed() bool {
// i.texture can be nil even when the image is not disposed,
// so we need to check if both are nil.
// See graphicsContext.setSize function.
return i.texture == nil && i.framebuffer == nil
}
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// ReplacePixels replaces the pixels of the image with p.
//
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// The given p must represent RGBA pre-multiplied alpha values. len(p) must equal to 4 * (image width) * (image height).
//
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// This function may be slow (as for implementation, this calls glTexSubImage2D).
func (i *Image) ReplacePixels(p []uint8) error {
if i.isDisposed() {
return errors.New("image is already disposed")
}
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// Don't set i.pixels here because i.pixels is used not every time.
i.pixels = nil
w, h := i.Size()
l := 4 * w * h
if len(p) != l {
return errors.New(fmt.Sprintf("p's length must be %d", l))
}
return i.texture.ReplacePixels(glContext, p)
}
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// A DrawImageOptions represents options to render an image on an image.
type DrawImageOptions struct {
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ImageParts ImageParts
GeoM GeoM
ColorM ColorM
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// Deprecated (as of 1.1.0-alpha): Use ImageParts instead.
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Parts []ImagePart
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}
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// NewImage returns an empty image.
//
// NewImage generates a new texture and a new framebuffer.
// Be careful that image objects will never be released
// even though nothing refers the image object and GC works.
// It is because there is no way to define finalizers for Go objects if you use GopherJS.
func NewImage(width, height int, filter Filter) (*Image, error) {
texture, err := graphics.NewTexture(glContext, width, height, glFilter(glContext, filter))
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if err != nil {
return nil, err
}
framebuffer, err := graphics.NewFramebufferFromTexture(glContext, texture)
if err != nil {
// TODO: texture should be removed here?
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return nil, err
}
img := &Image{framebuffer: framebuffer, texture: texture}
runtime.SetFinalizer(img, (*Image).Dispose)
if err := img.Clear(); err != nil {
return nil, err
}
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return img, nil
}
// NewImageFromImage creates a new image with the given image (img).
//
// NewImageFromImage generates a new texture and a new framebuffer.
// Be careful that image objects will never be released
// even though nothing refers the image object and GC works.
// It is because there is no way to define finalizers for Go objects if you use GopherJS.
func NewImageFromImage(img image.Image, filter Filter) (*Image, error) {
texture, err := graphics.NewTextureFromImage(glContext, img, glFilter(glContext, filter))
if err != nil {
return nil, err
}
framebuffer, err := graphics.NewFramebufferFromTexture(glContext, texture)
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if err != nil {
// TODO: texture should be removed here?
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return nil, err
}
eimg := &Image{framebuffer: framebuffer, texture: texture}
runtime.SetFinalizer(eimg, (*Image).Dispose)
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return eimg, nil
}