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Add basic image rendering support (unidoc#266)
* Add render package * Add text state * Add more text operators * Remove unnecessary files * Add text font * Add custom text render method * Improve text rendering method * Rename text state methods * Refactor and document context interface * Refact text begin/end operators * Fix graphics state transformations * Keep original font when doing font substitution * Take page cropbox into account * Revert to substitution font if original font measurement is 0 * Add font substitution package * Implement addition transform.Point methods * Use transform.Point in the image context package * Remove unneeded functionality from the render image package * Fix golint notices in the image rendering package * Fix go vet notices in the render package * Fix golint notices in the top-level render package * Improve render context package documentation * Document context text state struct. * Document context text font struct. * Minor logging improvements * Add license disclaimer to the render package files * Avoid using package aliases where possible * Change style of section comments * Adapt render package import style to follow the developer guide * Improve documentation for the internal matrix implementation * Update render package dependency versions * Apply crop box post render * Account for offseted media boxes * Improve metrics of rendered characters * Fix text matrix translation * Change priority of fonts used for measuring rendered characters * Skip invalid m and l operators on image rendering * Small fix for v operator * Fix rendered characters spacing issues * Refactor naming of internal render packages
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,14 +1,12 @@ | ||
| module github.com/unidoc/unipdf/v3 | ||
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| require ( | ||
| github.com/adrg/sysfont v0.1.0 | ||
| github.com/boombuler/barcode v1.0.0 | ||
| github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 | ||
| github.com/gunnsth/pkcs7 v0.0.0-20181213175627-3cffc6fbfe83 | ||
| github.com/stretchr/testify v1.3.0 | ||
| golang.org/x/crypto v0.0.0-20190605123033-f99c8df09eb5 | ||
| golang.org/x/image v0.0.0-20181116024801-cd38e8056d9b | ||
| golang.org/x/lint v0.0.0-20190409202823-959b441ac422 // indirect | ||
| golang.org/x/net v0.0.0-20190606173856-1492cefac77f // indirect | ||
| golang.org/x/sys v0.0.0-20190606203320-7fc4e5ec1444 // indirect | ||
| golang.org/x/text v0.3.2 | ||
| golang.org/x/tools v0.0.0-20190606174628-0139d5756a7d // indirect | ||
| ) |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,106 @@ | ||
| /* | ||
| * This file is subject to the terms and conditions defined in | ||
| * file 'LICENSE.md', which is part of this source code package. | ||
| */ | ||
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| package render | ||
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| import ( | ||
| "errors" | ||
| "fmt" | ||
| "image" | ||
| "image/draw" | ||
| "image/jpeg" | ||
| "image/png" | ||
| "os" | ||
| "path/filepath" | ||
| "strings" | ||
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| "github.com/unidoc/unipdf/v3/model" | ||
| "github.com/unidoc/unipdf/v3/render/internal/context/imagerender" | ||
| ) | ||
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| // ImageDevice is used to render PDF pages to image targets. | ||
| type ImageDevice struct { | ||
| renderer | ||
| } | ||
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| // NewImageDevice returns a new image device. | ||
| func NewImageDevice() *ImageDevice { | ||
| return &ImageDevice{} | ||
| } | ||
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| // Render converts the specified PDF page into an image and returns the result. | ||
| func (d *ImageDevice) Render(page *model.PdfPage) (image.Image, error) { | ||
| // Get page dimensions. | ||
| mbox, err := page.GetMediaBox() | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
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| // Render page. | ||
| width, height := mbox.Llx+mbox.Width(), mbox.Lly+mbox.Height() | ||
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| ctx := imagerender.NewContext(int(width), int(height)) | ||
| if err := d.renderPage(ctx, page); err != nil { | ||
| return nil, err | ||
| } | ||
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| // Apply crop box, if one exists. | ||
| img := ctx.Image() | ||
| if box := page.CropBox; box != nil { | ||
| // Calculate crop bounds and crop start position. | ||
| cropBounds := image.Rect(0, 0, int(box.Width()), int(box.Height())) | ||
| cropStart := image.Pt(int(box.Llx), int(height-box.Ury)) | ||
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| // Crop image. | ||
| cropImg := image.NewRGBA(cropBounds) | ||
| draw.Draw(cropImg, cropBounds, img, cropStart, draw.Src) | ||
| img = cropImg | ||
| } | ||
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| return img, nil | ||
| } | ||
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| // RenderToPath converts the specified PDF page into an image and saves the | ||
| // result at the specified location. | ||
| func (d *ImageDevice) RenderToPath(page *model.PdfPage, outputPath string) error { | ||
| image, err := d.Render(page) | ||
| if err != nil { | ||
| return err | ||
| } | ||
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| extension := strings.ToLower(filepath.Ext(outputPath)) | ||
| if extension == "" { | ||
| return errors.New("could not recognize output file type") | ||
| } | ||
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| switch extension { | ||
| case ".png": | ||
| return savePNG(outputPath, image) | ||
| case ".jpg", ".jpeg": | ||
| return saveJPG(outputPath, image, 100) | ||
| } | ||
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| return fmt.Errorf("unrecognized output file type: %s", extension) | ||
| } | ||
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| func savePNG(path string, image image.Image) error { | ||
| file, err := os.Create(path) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| defer file.Close() | ||
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| return png.Encode(file, image) | ||
| } | ||
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| func saveJPG(path string, image image.Image, quality int) error { | ||
| file, err := os.Create(path) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| defer file.Close() | ||
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| return jpeg.Encode(file, image, &jpeg.Options{Quality: quality}) | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,47 @@ | ||
| /* | ||
| * This file is subject to the terms and conditions defined in | ||
| * file 'LICENSE.md', which is part of this source code package. | ||
| */ | ||
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| package context | ||
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| import "image/color" | ||
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| // FillRule represents the fill style used by a context instance. | ||
| type FillRule int | ||
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| // Fill rules. | ||
| const ( | ||
| FillRuleWinding FillRule = iota | ||
| FillRuleEvenOdd | ||
| ) | ||
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| // LineCap represents the line cap style used by a context instance. | ||
| type LineCap int | ||
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| // Line cap styles. | ||
| const ( | ||
| LineCapRound LineCap = iota | ||
| LineCapButt | ||
| LineCapSquare | ||
| ) | ||
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| // LineJoin represents the line join style used by a context instance. | ||
| type LineJoin int | ||
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| // Line join styles. | ||
| const ( | ||
| LineJoinRound LineJoin = iota | ||
| LineJoinBevel | ||
| ) | ||
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| // Pattern represents a pattern which can be rendered by a context instance. | ||
| type Pattern interface { | ||
| ColorAt(x, y int) color.Color | ||
| } | ||
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| // Gradient represents a gradient pattern which can be rendered by a context instance. | ||
| type Gradient interface { | ||
| Pattern | ||
| AddColorStop(offset float64, color color.Color) | ||
| } |
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