Shulou(Shulou.com)06/03 Report--

I am basing my code on the p_w_picpaths1 example and I have changed

The p_w_picpath 'partner' shape from an ellipse to a rectangle.

The partner rectangle comes out at X,Y and scales and rotates

But the top left-hand corner of the p_w_picpath is always stuck at

(xmeny) = 3D (0pr 0). Only the part of the p_w_picpath that overlaps the=20

Rectangle is visible, but that part scales and rotates properly.=20

When there is no overlap, there is no p_w_picpath.

I do not understand much of the the p_w_picpath2 example, so I am

Lost as to what might be.the cause. Code is attached.

Would be most grateful for help and/or example code.

Void p_w_picpath (HAGG * h, int x, int y, TCHAR * imgfilename)

{

If (! loadp_w_picpath (h, imgfilename)) / / sets p_w_picpath details in h

{

Return

}

Agg::rendering_buffer rbuf (h-> pixels

H-> frame_width, = 20

H-> frame_height, = 20

-(h-> frame_width * h-> bytesperpixel); = 20

Typedef agg::renderer_base renderer_base

Typedef agg::renderer_base =

Renderer_base_pre

Typedef agg::renderer_scanline_aa_solid =

Renderer_solid

Pixfmt pixf (rbuf)

Pixfmt_pre pixf_pre (rbuf)

Renderer_base rb (pixf)

Renderer_base_pre rb_pre (pixf_pre)

Renderer_solid rs (rb)

Rb.clear (agg::rgba (1.0,1.0,1.0))

Agg::rasterizer_scanline_aa pf

Agg::scanline_u8 sl

IMGINFO * I = 3D & h-> imgs [0]

Double imgwd = 3D I-> width; / / p_w_picpath width

Double imght = 3D I-> height; / / p_w_picpath height

Agg::trans_affine src_mtx

Src_mtx * = 3D agg::trans_affine_translation (- xmai Mury)

Src_mtx * = 3D agg::trans_affine_rotation (- h-> t.angle); / / in radians

Src_mtx * = 3D agg::trans_affine_scaling (h-> t.scalex, h-> t.scaley)

Src_mtx * = 3D agg::trans_affine_translation (xQuery y)

Agg::trans_affine img_mtx

Img_mtx * = 3D agg::trans_affine_translation (- xmai Mury)

Img_mtx * = 3D agg::trans_affine_rotation (- h-> t.angle)

Img_mtx * = 3D agg::trans_affine_scaling (h-> t.scalex, h-> t.scaley)

Img_mtx * = 3D agg::trans_affine_translation (xQuery y)

Img_mtx.invert ()

Typedef agg::span_allocator span_alloc_type

Span_alloc_type sa

Typedef agg::span_interpolator_linear interpolator_type

Interpolator_type interpolator (img_mtx)

/ / "hardcoded" bilinear filter

Typedef agg::span_p_w_picpath_filter_rgb_bilinear =

Span_gen_type

Typedef agg::renderer_scanline_aa =

Renderer_type

Agg::rendering_buffer rbuf_img (I-> pixels

(int) imgwd, = 20

(int) imght, = 20

-I-> stride); = 20

Span_gen_type sg (sa,=20

Rbuf_img, / / rendering buf with p_w_picpath pixels

Agg::rgba_pre (0,0.4,0,0.5)

Interpolator)

Renderer_type ri (rb_pre, sg)

Agg::path_storage path; / / partner rectangle

Path.move_to (XBI y)

Path.line_to (x+imgwd, y)

Path.line_to (x+imgwd, y+imght)

Path.line_to (x, y+imght)

Path.close_polygon ()

Agg::conv_transform tr (path, src_mtx)

= 20

Pf.add_path (tr)

Agg::render_scanlines (pf, sl, ri)

}

Static void drawp_w_picpath ()

{

RECT rt

GetClientRect (hwndmain, & rt)

Int width = 3D rt.right-rt.left

Int height = 3D rt.bottom-rt.top

HAGG * h = 3D gethandle (mybuf, width, height, 4)

Settrans_scale (h, scale)

Settrans_rotate (h, degrees)

/ / p_w_picpath (h, 2050, "bmpeivor.bmp"); / / does not work

P_w_picpath (h, 0B0, "bmpeivor.bmp"); / / works

Display (h, hwndmain); / / on screen

}

The author's answer:

Transforming p_w_picpaths is tricky, especially proper calculation of the affine

Matrix.

But first, if you don't need to transform it you can directly copy or blend

The p_w_picpath, it will work much faster. See renderer_base::copy_from ()

Blend_from ().

For the transformer there's a simple way of calculating the matrix as a

Parallelogram, see p_w_picpath_perspective.cpp

/ / Note that we consruct an affine matrix that transforms

/ / a parallelogram to a rectangle, i.e., it's inverted.

/ / It's actually the same as:

/ / tr (0,0, img_width, img_height, para); tr.invert ()

Agg::trans_affine tr (para, 0,0, img_width, img_height)

Where "para" is double [6] that defines 3 point of the parallelogram.

Perplexity:

I have replaced

Agg::path_storage path; / / partner rectangle

Path.move_to (XBI y)

Path.line_to (x+imgwd, y)

Pathmline_to (x+imgwd, y+imght)

Path.line_to (x, y+imght)

Path.close_polygon ()

Agg::conv_transform tr (path, src_mtx)

Pf.add_path (tr)

Agg::render_scanlines (pf, sl, ri)

At the and of my p_w_picpath proc (code of the whole proc is at

The end of my original post (and at the end of this email))

By

Double para [6]

= {0100, 0jue 0, 100.0}; / / 3 points (0100) (0je 0) and (100jue 0)

Agg::trans_affine tr (para, 0,0, imgwd, imght)

Pf.add_path (tr)

Agg::render_scanlines (pf, sl, ri)

Q1. Is this the right way?

Q2. What should the para points be expressed as functions of

P_w_picpath top-left hand corner, p_w_picpath width and p_w_picpath height, i.e.

X,y, imgwd, imght?

My test cases includes p_w_picpath (xmemy) = (0penol 0), so I defined para points

(0100), (0) and (100) just to see what would happen.

But got compilation errors:

..\ agg23\ include\ agg_rasterizer_scanline_aa.h: error C2039: 'rewind':

Is not a member of 'trans_affine'

..\ agg23\ include\ agg_trans_affine.h (88): see declaration of

'trans_affine'

And one more very similar: 'vertex': is not a member of' trans_affine'

The author's answer:

> double para [6] = {0100, 0jue 0100jin0}; / / 3 points (0100) (0Jing 0)

> and (100Pol 0)

> agg::trans_affine mtx (para, 0,0, imgwd, imght)

> agg::path_storage path; / / partner rectangle

> path.move_to (XBI y)

> path.line_to (x+imgwd, y)

> path.line_to (x+imgwd, y+imght)

> path.line_to (x, y+imght)

> path.close_polygon ()

> agg::conv_transform trans (path

> mtx)

>

> pf.add_path (trans); / / Note you add "trans"

>

> Then, if you want your p_w_picpath to fit exactly your parallelogram path (you

> also may want to do differently!), you need to create a copy of the matrix

> and invert it:

>

> agg::trans_affine img_mtx (mtx)

> img_mtx.invert ()

ITunm sorry, Ken, this is not correct; I have confused myself, so, please

Discard the code above. :)

So, suppose you have an p_w_picpath of imgwd, imght and a destination

Parallelogram. To define the parallelogram you need 3 points, x1jiny1-bottom

Left, x2jiny2-bottom right, x3jiny3-top right. The parallelogram can also

Define a 2D affine matrix: rotation, scaling, translation and skewing. You

Can rasterize your destination parallelogram directly:

Agg::rasterizer_scanline_aa ras

Ras.move_to_d (x1Query y1)

Ras.line_to_d (x2jiny2)

Ras.line_to_d (x3ther y3)

Ras.line_to_d (x1 + x3-x2, y1 + y3-y2)

So that, you can draw a solid parallelogram (well, you can also use the

Path_storage if you want).

To map an p_w_picpath to it you need to create the matrix:

Double para [6] = {x1meng y1pr x2jiny2pr x3je y3}

Agg::trans_affine img_mtx (0,0, imgwd, imght, para)

Img_mtx.invert ()

Or, which is the same:

Double para [6] = {x1meng y1pr x2jiny2pr x3je y3}

Agg::trans_affine img_mtx (para, 0,0, imgwd, imght)

The first one construicts a matrix to transform a rectangle to an a

Parellelogram, the second one-parallelogram to rectangle. The p_w_picpath

Transformer requires namely inverse matrix, so that, you transform your

Parallelogram (destination) to rectangle (p_w_picpath).

Technically that's it. But you may want to apply additional transformations.

To do that you will need two matrices:

Agg::trans_affine master_mtx

Master_mtx * = agg::trans_affine_translation (. . .)

Master_mtx * = agg::trans_affine_rotation (. . .)

. . .

Agg::rasterizer_scanline_aa ras

Agg::path_storage path; / / partner rectangle

Path.move_to (x1Query y1)

Path.line_to (x2jiny2)

Path.line_to (x3ther y3)

Path.line_to (x1 + x3-x2, y1 + y3-y2)

Path.close_polygon ()

Agg::conv_transform trans (path

Master_mtx)

Then you prepare the p_w_picpath matrix:

Double para [6] = {x1meng y1pr x2jiny2pr x3je y3}

Agg::trans_affine img_mtx (0,0, imgwd, imght, para)

Img_mtx * = master_mtx; / /! Integrate the master transforms

Img_mtx.invert ()

Ras.add_path (trans)

. . .Render

Now, whatever transformations you use in the master_mtx à they will be

Synchronized with the p_w_picpath.

Sorry for the delay, I was kinda busy last time. And besides, iTunm suffering

From constant problems with the Internet (Verizon in NYC sucks, iTunm)

Switching to cable).

Well, I understand everyone is busy, but could someone else answer the

Questions too?

First, you need to understand that a path is the primary thing in AGG.

Without path you can't draw anything. So that, to rotate an p_w_picpath you need

To create a respective path as if you wanted to fill this area with a solid

Color. And then, you just substitute an p_w_picpath renderer for your solid fill.

Obviously, to transform the whole p_w_picpath you need to create a parallelogram

Path (a rectangle in particular). You can do that calculating the points

Manually:

Ras.move_to_d (x1, y1)

Ras.line_to_d (x2, y2)

. . .

You you can use transformations.

Next, trans_affine doesn't have any "VertexSource" interface, it can't

Generate vertices. It can only transform them: affine.transform (& x, & y); To

Add affine transformer into your pipeline you also need conv_transform:

Double para [6] = {0100, 0 points 0}; / / 3 points (0100) (0 minute 0) and

(100pi 0)

Agg::trans_affine mtx (para, 0,0, imgwd, imght)

Agg::path_storage path; / / partner rectangle

Path.move_to (XBI y)

Path.line_to (x+imgwd, y)

Path.line_to (x+imgwd, y+imght)

Path.line_to (x, y+imght)

Path.close_polygon ()

Agg::conv_transform trans (path, mtx)

Pf.add_path (trans); / / Note you add "trans"

Then, if you want your p_w_picpath to fit exactly your parallelogram path (you

Also may want to do differently!), you need to create a copy of the matrix

And invert it:

Agg::trans_affine img_mtx (mtx)

Img_mtx.invert ()

Well, I realize that it all is pretty confusing. But this kind of a design

Is most flexible.

Extracted from: http://sourceforge.net/p/vector-agg/mailman/vector-agg-general/?viewmonth=200511&page=0

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