github.com/kintar/etxt@v0.0.9/examples/gtxt/mix_modes/main.go (about)

     1  //go:build gtxt
     2  
     3  package main
     4  
     5  import "os"
     6  import "image"
     7  import "image/color"
     8  import "image/png"
     9  import "path/filepath"
    10  import "log"
    11  import "fmt"
    12  
    13  import "github.com/kintar/etxt"
    14  
    15  // Must be compiled with '-tags gtxt'
    16  
    17  // TODO: it would be nice to make an extra example with semi-transparent
    18  //       colors, mostly to confirm that all the modes are working as
    19  //       expected, which I don't trust very much.
    20  
    21  func main() {
    22  	// get font path
    23  	if len(os.Args) != 2 {
    24  		msg := "Usage: expects one argument with the path to the font to be used\n"
    25  		fmt.Fprint(os.Stderr, msg)
    26  		os.Exit(1)
    27  	}
    28  
    29  	// parse font
    30  	font, fontName, err := etxt.ParseFontFrom(os.Args[1])
    31  	if err != nil {
    32  		log.Fatal(err)
    33  	}
    34  	fmt.Printf("Font loaded: %s\n", fontName)
    35  
    36  	// create cache
    37  	cache := etxt.NewDefaultCache(1024 * 1024 * 1024) // 1GB cache
    38  
    39  	// create and configure renderer
    40  	renderer := etxt.NewStdRenderer()
    41  	renderer.SetCacheHandler(cache.NewHandler())
    42  	renderer.SetSizePx(24)
    43  	renderer.SetFont(font)
    44  	renderer.SetAlign(etxt.YCenter, etxt.XCenter)
    45  	renderer.SetColor(color.RGBA{0, 0, 0, 255}) // black
    46  
    47  	// create target image and fill it with different colors
    48  	outImage := image.NewRGBA(image.Rect(0, 0, 720, 300))
    49  	for i := 0; i < 720*100*4; i += 4 { // first 100 lines cyan
    50  		//outImage.Pix[i + 0] = 0
    51  		outImage.Pix[i+1] = 255
    52  		outImage.Pix[i+2] = 255
    53  		outImage.Pix[i+3] = 255
    54  	}
    55  	for i := 720 * 100 * 4; i < 720*200*4; i += 4 { // next 100 lines magenta
    56  		outImage.Pix[i+0] = 255
    57  		//outImage.Pix[i + 1] = 0
    58  		outImage.Pix[i+2] = 255
    59  		outImage.Pix[i+3] = 255
    60  	}
    61  	for i := 720 * 200 * 4; i < 720*300*4; i += 4 { // next 100 lines yellow
    62  		outImage.Pix[i+0] = 255
    63  		outImage.Pix[i+1] = 255
    64  		//outImage.Pix[i + 2] = 0
    65  		outImage.Pix[i+3] = 255
    66  	}
    67  
    68  	// set target
    69  	renderer.SetTarget(outImage)
    70  
    71  	// draw first row of mix modes
    72  	offX, offY := 180, 100
    73  	x := offX / 2
    74  	y := offY / 2
    75  	renderer.Draw("over", x, y)
    76  
    77  	x += offX
    78  	renderer.SetMixMode(etxt.MixCut)
    79  	renderer.Draw("cut", x, y)
    80  
    81  	x += offX
    82  	renderer.SetMixMode(etxt.MixReplace)
    83  	renderer.Draw("replace", x, y)
    84  
    85  	x += offX
    86  	renderer.SetMixMode(etxt.MixFiftyFifty)
    87  	renderer.Draw("50%-50%", x, y)
    88  
    89  	// draw second row of mix modes
    90  	y += offY
    91  	x = offX / 2
    92  	renderer.SetColor(color.RGBA{0, 255, 255, 255})
    93  	renderer.SetMixMode(etxt.MixSub)
    94  	renderer.Draw("subtract", x, y)
    95  
    96  	x += offX
    97  	renderer.SetMixMode(etxt.MixAdd)
    98  	renderer.Draw("add", x, y)
    99  
   100  	x += offX
   101  	renderer.SetMixMode(etxt.MixMultiply)
   102  	renderer.Draw("multiply", x, y)
   103  
   104  	x += offX
   105  	renderer.SetMixMode(etxt.MixOver)
   106  	renderer.Draw("over", x, y)
   107  
   108  	// draw third row of mix modes
   109  	y += offY
   110  	x = offX / 2
   111  	renderer.SetColor(color.RGBA{255, 0, 0, 255})
   112  	renderer.SetMixMode(etxt.MixOver)
   113  	renderer.Draw("over", x, y)
   114  
   115  	x += offX
   116  	renderer.SetMixMode(etxt.MixFiftyFifty)
   117  	renderer.Draw("50%-50%", x, y)
   118  
   119  	x += offX
   120  	renderer.SetMixMode(etxt.MixSub)
   121  	renderer.Draw("subtract", x, y)
   122  
   123  	x += offX
   124  	renderer.SetMixMode(etxt.MixMultiply)
   125  	renderer.Draw("multiply", x, y)
   126  
   127  	// store image as png
   128  	filename, err := filepath.Abs("gtxt_mix_modes.png")
   129  	if err != nil {
   130  		log.Fatal(err)
   131  	}
   132  	fmt.Printf("Output image: %s\n", filename)
   133  	file, err := os.Create(filename)
   134  	if err != nil {
   135  		log.Fatal(err)
   136  	}
   137  	err = png.Encode(file, outImage)
   138  	if err != nil {
   139  		log.Fatal(err)
   140  	}
   141  	err = file.Close()
   142  	if err != nil {
   143  		log.Fatal(err)
   144  	}
   145  	fmt.Print("Program exited successfully.\n")
   146  }