fade in / Fade out in image scroller

[ts4pi]

Hi, is it possible to change brightness in Imagescroller while running ? I would like to have a fade in / fade out or blinking Best regards Thomas

[hzeller]

You have to implement that yourself, but should be a nice small exercise. There is a SetBrightness() call that takes values from 0..100 (essentially percent).

Note that setting the brigthness requires to set all the pixels again, but if you scroll the image, that happens anyway.

[soyxan]

I want to do this fade in and fade out with whatever is drawn on the Canvas (text, images, etc.) As you said I need to SetPixel again in order to get the new brightness. Instead of drawing the image again, I was wondering if I just can get the pixels color directly from the current canvas (¿¿GetPixel??), SetBrightness to a new Canvas, SetPixel to the new Canvas and then SwapOnVSync with the new Canvas.

[hzeller]

You can't get the current pixel color, as the RGBMatrix immediately translates it into the needed underlying bit-pattern (this makes it fast to display), but there is no translation-back implemented.

So if you want to do that, you might want to implement a Canvas interface that keeps a copy of the original pixel color on SetPixel() (storing in a 2-dimenstional array essentially), then delegates to some underlying Canvas (the FrameCanvas of the RGBMatrix). Then you can implement a method GetPixel() on your Canvas implementation that allows you to get the original color.

[soyxan]

Following your suggestion I've tried is to make a derived class of FrameCanvas that way:

class FrameCanvas2 : public FrameCanvas {
public:
    void SetPixel(int x, int y, uint8_t red, uint8_t green, uint8_t blue){
        printf("SetPixel");
        if (pixels_.size()==0) pixels_.resize(this->width(), vector<rgb_matrix::Color> (this->height(), rgb_matrix::Color(0,0,0)));
        pixels_[x][y].r = red;
        pixels_[x][y].g = green;
        pixels_[x][y].b = blue;
        FrameCanvas::SetPixel(x, y, red, green, blue);
    }
    void GetPixel(int x, int y, uint8_t * red, uint8_t * green, uint8_t * blue){
        *red = pixels_[x][y].r;
        *green = pixels_[x][y].g;
        *blue = pixels_[x][y].b;
    }
private:
    std::vector<std::vector<rgb_matrix::Color> > pixels_;
};

But my implementation of SetPixel is never called, being called the base class SetPixel instead (I have tested calling rgb_matrix::DrawText passing my Framecanvas2 implementation, and the text is drawn on the panels but my "printf" is never shown).

I am sure that there is a better way to do it, but I am not that "good" with C++, can you give me some directions? Thanks a lot!

[hzeller]

Don't derive, make a delegation instead. Then you can wrap the canvas coming from the RGBMatrix

On Apr 28, 2017 16:51, "soyxan" notifications@github.com wrote:

Following your suggestion I've tried is to make a derived class of FrameCanvas that way:

class FrameCanvas2 : public FrameCanvas { public: void SetPixel(int x, int y, uint8_t red, uint8_t green, uint8t blue){ printf("SetPixel"); if (pixels.size()==0) pixels_.resize(this->width(), vector (this->height(), rgbmatrix::Color(0,0,0))); pixels[x][y].r = red; pixels[x][y].g = green; pixels[x][y].b = blue; FrameCanvas::SetPixel(x, y, red, green, blue); } void GetPixel(int x, int y, uint8_t red, uint8_t green, uint8t blue){ red = pixels[x][y].r; green = pixels_[x][y].g; blue = pixels_[x][y].b; } private: std::vector<std::vector > pixels_; };

But my implementation fo SetPixel is never called, being called the base class SetPixel instead (I have tested calling rgb_matrix::DrawText with my Framecanvas2 implementation, and the text is drawn on the panels but my "printf" is never shown).

I am sure that there is a better way to do it, but I am not that "good" with C++, can you give me some directions? Thanks a lot!

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[soyxan]

Do you mean something like that? (I get plenty of errors when compiling)

class FrameCanvas2 : public FrameCanvas {
public:
    FrameCanvas2(FrameCanvas *c) {
        framecanvas_ = c;
    }

    void SetPixel(int x, int y, uint8_t red, uint8_t green, uint8_t blue){
        printf("SetPixel");
        framecanvas_->SetPixel(x,y,red,green,blue)
    }
private:
    FrameCanvas* framecanvas_;
};

[hzeller]

FrameCanvas is a private implementation, you can't extend that. The overall interface is the Canvas, which you need to extend, roughtly like this:

class MyGetPixelCanvas : public rgb_matrix::Canvas {
public:
   MyGetPixelCanvas(FrameCanvas *canvas) : delegatee_(canvas) {}
   int width() const { return delegatee_->width(); }
   int height() const { return delegatee_->height(); }
   void SetBrightness(uint8_t b) { delegatee_->SetBrightness(b); }

    // etc., implement Clear(), Fill() as well by delegation

   void SetPixel(...) { /* your implementation storing away pixels, then */ delegatee_->SetPixel(...); }
   Color GetPixel(int x, int y) { /* your implementation */ }

private:
   FrameCanvas *const delegatee_;
};

Then you can wrap this canvas around a FrameCanvas:

MyGetPixelCanvas canvas(some_frame_canvas);
canvas.SetPixel(...)
canvas.SetBrightness(...);
canvas.GetPixel(...)

[soyxan]

I have implemented all the methods of Canvas class in my wrapper:

class FrameCanvas2 : public rgb_matrix::Canvas {
public:
    FrameCanvas2(rgb_matrix::Canvas *canvas) : delegatee_(canvas) {}
    int width() const { return delegatee_->width(); }
    int height() const { return delegatee_->height(); }
    void Fill(uint8_t red, uint8_t green, uint8_t blue) { delegatee_->Fill(red, green, blue);}
    void Clear() {delegatee_->Clear();}

    void SetPixel(int x, int y, uint8_t red, uint8_t green, uint8_t blue){
        printf("SetPixel");
        delegatee_->SetPixel(x,y,red,green,blue);
    }
    rgb_matrix::Color GetPixel(int x, int y)
    {

    }
private:
   Canvas *const delegatee_;
};

Now I will use it in my ThreadedCanvasManipulator implementation in order to draw some scrolling text:

class Texto : public ThreadedCanvasManipulator {
public:
    Texto(RGBMatrix *m, const char * texto) : ThreadedCanvasManipulator(m), matrix_(m), texto_(texto) {
        off_screen_canvas_ = new FrameCanvas2(m->CreateFrameCanvas());
    }
    void Run() {
        rgb_matrix::Color color(255, 255, 0);

        rgb_matrix::Font font;
        if (!font.LoadFont("/home/pi/matrix/fuentes/bebasneue.bdf")) {
            fprintf(stderr, "Couldn't load font");
            return;
        }
        int brightness = 100;

        off_screen_canvas_->SetBrightness(brightness);

        bool all_extreme_colors = brightness == 100;
        all_extreme_colors &= color.r == 0 || color.r == 255;
        all_extreme_colors &= color.g == 0 || color.g == 255;
        all_extreme_colors &= color.b == 0 || color.b == 255;
        if (all_extreme_colors)
        off_screen_canvas_->SetPWMBits(1);
        int x=off_screen_canvas_->width();
        int lentext=0;

        while (running() && !interrupt_received) {
            usleep(10 * 1000);
            off_screen_canvas_->Clear();
            lentext = rgb_matrix::DrawText(off_screen_canvas_, font, x, 0 + font.baseline(), color, texto_);
            off_screen_canvas_->SetPixel(10,10,255,0,0);
            /*off_screen_canvas_ = */matrix_->SwapOnVSync(off_screen_canvas_);
            x--;
            if (x<(-1*lentext)) x=off_screen_canvas_->width();
        }
    }

private:
    RGBMatrix *const matrix_;
    FrameCanvas2 *off_screen_canvas_;
    const char * texto_;
};

But the compiler says that it can't find matching function for off_screen_canvas->SetPwmBits, SwapOnVSync, etc. Do I have to implement those as well in my wrapper?

[soyxan]

Now I got it working. My FrameCanvas2 implemtation should be used only for calling SetPixel and GetPixel. For all other calls, FrameCanvas should be used.

Thanks for all your help!