submodule (fortplot_raster) fortplot_raster_impl !! Implementation of drawing primitives for raster_context. !! Contains: line, color, line_width, line_style, marker, arrow. use fortplot_raster_core, only: pt2px use fortplot_3d_axes, only: draw_3d_axes contains !! Drawing primitives module subroutine raster_draw_line(this, x1, y1, x2, y2) use fortplot_line_styles, only: scale_pattern_to_pixels, get_pattern_length class(raster_context), intent(inout) :: this real(wp), intent(in) :: x1, y1, x2, y2 real(wp) :: px1, py1, px2, py2 real(wp) :: scaled_pattern(20), scaled_length ! Transform coordinates to plot area (like matplotlib) ! Note: Raster Y=0 at top, so we need to flip Y coordinates px1 = (x1 - this%x_min)/(this%x_max - this%x_min)* & real(this%plot_area%width, wp) + real(this%plot_area%left, wp) py1 = real(this%plot_area%bottom + this%plot_area%height, wp) - & (y1 - this%y_min)/(this%y_max - & this%y_min)*real(this%plot_area%height, wp) px2 = (x2 - this%x_min)/(this%x_max - this%x_min)* & real(this%plot_area%width, wp) + real(this%plot_area%left, wp) py2 = real(this%plot_area%bottom + this%plot_area%height, wp) - & (y2 - this%y_min)/(this%y_max - & this%y_min)*real(this%plot_area%height, wp) ! Scale the point-based pattern to pixels for this line width and DPI, ! matching matplotlib (pattern_pt * line_width_pt * dpi / 72). scaled_pattern = this%raster%line_pattern call scale_pattern_to_pixels(scaled_pattern, this%raster%pattern_size, & this%raster%dpi, this%raster%current_line_width_pt) scaled_length = get_pattern_length(scaled_pattern, this%raster%pattern_size) ! Draw line with pattern support call draw_styled_line(this%raster%image_data, this%width, this%height, & px1, py1, px2, py2, & this%raster%current_r, this%raster%current_g, & this%raster%current_b, & this%raster%current_line_width, & this%raster%line_style, scaled_pattern, & this%raster%pattern_size, scaled_length, & this%raster%pattern_distance) end subroutine raster_draw_line module subroutine raster_set_color_context(this, r, g, b) class(raster_context), intent(inout) :: this real(wp), intent(in) :: r, g, b call this%raster%set_color(r, g, b) end subroutine raster_set_color_context module subroutine raster_set_line_width(this, width) !! Set line width for raster drawing with DPI-aware point-to-pixel scaling. !! Input width is in points (1pt = 1/72 inch). Converted to pixels via DPI. class(raster_context), intent(inout) :: this real(wp), intent(in) :: width real(wp) :: px if (width <= 0.0_wp) then this%raster%current_line_width = 1.0_wp this%raster%current_line_width_pt = 1.0_wp else px = pt2px(width, this%raster%dpi) this%raster%current_line_width = max(1.0_wp, px) this%raster%current_line_width_pt = width end if end subroutine raster_set_line_width module subroutine raster_set_line_style_context(this, style) !! Set line style for raster context class(raster_context), intent(inout) :: this character(len=*), intent(in) :: style call this%raster%set_line_style(style) end subroutine raster_set_line_style_context !! Marker drawing module subroutine raster_draw_marker(this, x, y, style, size) class(raster_context), intent(inout) :: this real(wp), intent(in) :: x, y character(len=*), intent(in) :: style real(wp), intent(in), optional :: size real(wp) :: px, py, scale integer(1) :: r, g, b associate (dsl => len_trim(style)); end associate scale = 1.0_wp if (present(size)) scale = marker_size_scale(size) ! Transform coordinates to plot area px = (x - this%x_min)/(this%x_max - this%x_min)*real(this%plot_area%width, wp) & + real(this%plot_area%left, wp) py = real(this%plot_area%bottom + this%plot_area%height, wp) - & (y - this%y_min)/(this%y_max - this%y_min)*real(this%plot_area%height, wp) call this%raster%get_color_bytes(r, g, b) ! Fixed marker centering for Issue #333: align markers with line centers ! Apply sub-pixel adjustment to match line drawing coordinate conventions call draw_raster_marker_by_style(this, px - 0.5_wp, py - 0.5_wp, style, scale) end subroutine raster_draw_marker module subroutine draw_raster_marker_by_style(this, px, py, style, scale) !! Draw marker using shared style dispatch logic (DRY compliance) class(raster_context), intent(inout) :: this real(wp), intent(in) :: px, py character(len=*), intent(in) :: style real(wp), intent(in) :: scale real(wp) :: marker_size marker_size = get_marker_size(style) * scale * this%raster%dpi / REFERENCE_DPI select case (trim(style)) case (MARKER_CIRCLE) call draw_circle_with_edge_face(this%raster%image_data, this%width, & this%height, px, py, marker_size, & this%raster%marker_edge_r, & this%raster%marker_edge_g, & this%raster%marker_edge_b, & this%raster%marker_edge_alpha, & this%raster%marker_face_r, & this%raster%marker_face_g, & this%raster%marker_face_b, & this%raster%marker_face_alpha, & this%raster%current_line_width) case (MARKER_SQUARE) call draw_square_with_edge_face(this%raster%image_data, this%width, & this%height, px, py, marker_size, & this%raster%marker_edge_r, & this%raster%marker_edge_g, & this%raster%marker_edge_b, & this%raster%marker_edge_alpha, & this%raster%marker_face_r, & this%raster%marker_face_g, & this%raster%marker_face_b, & this%raster%marker_face_alpha, & this%raster%current_line_width) case (MARKER_DIAMOND) call draw_diamond_with_edge_face(this%raster%image_data, this%width, & this%height, px, py, marker_size, & this%raster%marker_edge_r, & this%raster%marker_edge_g, & this%raster%marker_edge_b, & this%raster%marker_edge_alpha, & this%raster%marker_face_r, & this%raster%marker_face_g, & this%raster%marker_face_b, & this%raster%marker_face_alpha, & this%raster%current_line_width) case (MARKER_CROSS) call draw_x_marker(this%raster%image_data, this%width, & this%height, px, & py, marker_size, & this%raster%marker_edge_r, & this%raster%marker_edge_g, & this%raster%marker_edge_b, & this%raster%marker_edge_alpha, & this%raster%current_line_width) end select end subroutine draw_raster_marker_by_style module subroutine raster_set_marker_colors(this, edge_r, edge_g, edge_b, face_r, & face_g, face_b) class(raster_context), intent(inout) :: this real(wp), intent(in) :: edge_r, edge_g, edge_b real(wp), intent(in) :: face_r, face_g, face_b this%raster%marker_edge_r = edge_r this%raster%marker_edge_g = edge_g this%raster%marker_edge_b = edge_b this%raster%marker_edge_alpha = 1.0_wp ! Default to opaque this%raster%marker_face_r = face_r this%raster%marker_face_g = face_g this%raster%marker_face_b = face_b this%raster%marker_face_alpha = 1.0_wp ! Default to opaque end subroutine raster_set_marker_colors module subroutine raster_set_marker_colors_with_alpha(this, edge_r, edge_g, edge_b, & edge_alpha, & face_r, face_g, face_b, face_alpha) class(raster_context), intent(inout) :: this real(wp), intent(in) :: edge_r, edge_g, edge_b, edge_alpha real(wp), intent(in) :: face_r, face_g, face_b, face_alpha this%raster%marker_edge_r = edge_r this%raster%marker_edge_g = edge_g this%raster%marker_edge_b = edge_b this%raster%marker_edge_alpha = edge_alpha this%raster%marker_face_r = face_r this%raster%marker_face_g = face_g this%raster%marker_face_b = face_b this%raster%marker_face_alpha = face_alpha end subroutine raster_set_marker_colors_with_alpha !! Arrow drawing module subroutine raster_draw_arrow(this, x, y, dx, dy, size, style) !! Draw arrow head for streamplot arrows in raster backend class(raster_context), intent(inout) :: this real(wp), intent(in) :: x, y, dx, dy, size character(len=*), intent(in) :: style real(wp) :: arrow_length, arrow_width, norm_dx, norm_dy real(wp) :: perp_x, perp_y ! Perpendicular vector for arrow width real(wp) :: x1, y1, x2, y2, x3, y3 ! Triangle vertices real(wp) :: shaft_base_x, shaft_base_y real(wp) :: magnitude integer(1) :: r, g, b real(wp) :: px, py, ddx, ddy associate (dsl => len_trim(style)); end associate ! Transform data coordinates to pixel coordinates px = (x - this%x_min)/(this%x_max - this%x_min)*real(this%plot_area%width, wp) & + real(this%plot_area%left, wp) py = real(this%plot_area%bottom + this%plot_area%height, wp) - & (y - this%y_min)/(this%y_max - this%y_min)*real(this%plot_area%height, wp) ! Scale direction components to pixel units (account for inverted Y) ddx = dx*(real(this%plot_area%width, wp)/max(1.0_wp, (this%x_max - this%x_min))) ddy = -dy*(real(this%plot_area%height, wp)/max(1.0_wp, (this%y_max - & this%y_min))) ! Normalize direction vector magnitude = sqrt(ddx*ddx + ddy*ddy) if (magnitude < 1e-10_wp) return ! Avoid division by zero norm_dx = ddx/magnitude norm_dy = ddy/magnitude ! Calculate arrow dimensions based on size. Slim head aspect ! (full width ~0.7*length) matches matplotlib's head_width/head_length. arrow_length = size*8.0_wp ! Scale factor for reasonable arrow size arrow_width = arrow_length*0.35_wp ! Calculate perpendicular vector for arrow width perp_x = -norm_dy perp_y = norm_dx ! Calculate triangle vertices for arrow head (tip at pixel coords) x1 = px y1 = py ! Base vertices of arrow head x2 = px - arrow_length*norm_dx + arrow_width*perp_x y2 = py - arrow_length*norm_dy + arrow_width*perp_y x3 = px - arrow_length*norm_dx - arrow_width*perp_x y3 = py - arrow_length*norm_dy - arrow_width*perp_y ! Shaft base: vector start = tip - magnitude*norm (shaft = magnitude - arrow_length) shaft_base_x = px - magnitude*norm_dx shaft_base_y = py - magnitude*norm_dy ! Get current color for filling call this%raster%get_color_bytes(r, g, b) call draw_line_distance_aa(this%raster%image_data, this%width, this%height, & shaft_base_x, shaft_base_y, px, py, & real(r, wp)/255.0_wp, real(g, wp)/255.0_wp, & real(b, wp)/255.0_wp, 1.0_wp) ! Draw filled triangle arrow head call fill_triangle(this%raster%image_data, this%width, this%height, & x1, y1, x2, y2, x3, y3, r, g, b) ! Mark that arrows have been rendered this%has_rendered_arrows = .true. this%uses_vector_arrows = .false. this%has_triangular_arrows = .true. end subroutine raster_draw_arrow module subroutine raster_draw_arrowhead(this, x, y, dx, dy, size, style) !! Draw a streamplot-style open arrowhead at (x, y), matching !! matplotlib's FancyArrowPatch "->" glyph: two thin strokes meeting !! at the tip, in the streamline color and line width. (dx, dy) is a !! unit direction in data space; size is matplotlib's arrowsize and !! controls the head length in pixels, independent of the data range. class(raster_context), intent(inout) :: this real(wp), intent(in) :: x, y, dx, dy, size character(len=*), intent(in) :: style real(wp), parameter :: head_half_angle = 0.5235987756_wp ! 30 degrees real(wp) :: head_length, line_w real(wp) :: norm_dx, norm_dy, magnitude real(wp) :: px, py, ddx, ddy real(wp) :: cos_a, sin_a real(wp) :: lx, ly, rx, ry associate (dsl => len_trim(style)); end associate ! Transform tip position to pixel coordinates. px = (x - this%x_min)/(this%x_max - this%x_min)*real(this%plot_area%width, wp) & + real(this%plot_area%left, wp) py = real(this%plot_area%bottom + this%plot_area%height, wp) - & (y - this%y_min)/(this%y_max - this%y_min)*real(this%plot_area%height, wp) ! Convert the data-space unit direction to a screen-space direction ! (the Y axis is flipped and the axes have independent pixel scales), ! then renormalize so the head length is a fixed pixel quantity. ddx = dx*(real(this%plot_area%width, wp)/max(1.0_wp, (this%x_max - this%x_min))) ddy = -dy*(real(this%plot_area%height, wp)/max(1.0_wp, (this%y_max - & this%y_min))) magnitude = sqrt(ddx*ddx + ddy*ddy) if (magnitude < 1.0e-10_wp) return norm_dx = ddx/magnitude norm_dy = ddy/magnitude ! matplotlib draws the "->" head from the tip backwards. mutation_scale ! is 10*arrowsize points; the visible head spans roughly half of that. head_length = size*6.0_wp line_w = max(1.0_wp, this%raster%current_line_width) cos_a = cos(head_half_angle) sin_a = sin(head_half_angle) ! Two backward strokes rotated by +/- the half angle from the ! reverse direction, forming an open V whose vertex is the tip. lx = px - head_length*(norm_dx*cos_a - norm_dy*sin_a) ly = py - head_length*(norm_dy*cos_a + norm_dx*sin_a) rx = px - head_length*(norm_dx*cos_a + norm_dy*sin_a) ry = py - head_length*(norm_dy*cos_a - norm_dx*sin_a) call draw_line_distance_aa(this%raster%image_data, this%width, this%height, & px, py, lx, ly, this%raster%current_r, & this%raster%current_g, this%raster%current_b, line_w) call draw_line_distance_aa(this%raster%image_data, this%width, this%height, & px, py, rx, ry, this%raster%current_r, & this%raster%current_g, this%raster%current_b, line_w) this%has_rendered_arrows = .true. this%uses_vector_arrows = .true. this%has_triangular_arrows = .false. end subroutine raster_draw_arrowhead end submodule fortplot_raster_impl